• Environmental engineer
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• s.65
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• pp.18-24
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• 1992

우리나라와 같이 전기제품의 수출이 전체수출의 많은 부분을 차지하는 상태에서는 전자파장해의 정확한 측정기술의 개발, 전자파대책 부품과 기술개발 등의 연구가 요구되고 있다. 특히 레이저, 마이크로 웨이브 오븐, 고광도 광원 등과 같은 방사선을 이용하거나 발산하는 전자 창작품의 생산이 급격한 성장을 보이고 있는 가운데 비전리 방사선에 의한 공중건강에 관심이 높아지고 있다.

• 대한방사선방어학회:학술대회논문집
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• 2009.11a
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• pp.190-191
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• 2009

• Nuclear industry
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• v.7 no.5 s.51
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• pp.82-84
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• 1987

원자력발전소에서의 방사선관리의 내용으로는 발전소주변에서의 환경방사선의 감시, 발전소의 관리구역에 종사하는 작업원의 방사선량 파악등 방사선작업관리, 프로세스방사선모니터의 감시에 의한 플랜트의 운전상황의 파악등으로 대별된다.

• Journal of Radiation Industry
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• v.6 no.1
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• pp.61-65
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• 2012

Polyacrylonitrile (PAN) is one of the most widely used precursor polymers for making high performance carbon fibers. Conversion of PAN fibers to good quality carbon fibers requires an essential stabilization step prior to carbonization. Electron beam irradiation is an excellent technique for modifying the physical properties of materials. This study aimed to elucidate the effects of electron beam irradiation on the stabilization reactions of PAN nanofibers. FT-IR analysis indicated that the stabilization of irradiated PAN nanofibers was initiated at a lower temperature. The TG curve of PAN nanofibers showed a significant decrease of weight loss step between 280 and $320^{\circ}C$. In the case of irradiated PAN nanofibers, weight loss sudden weight did not loss occurs.

• Journal of Radiation Industry
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• v.5 no.1
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• pp.41-46
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• 2011

Polyacrylonitrile (PAN) fibers are the most widely used precursor of the materials for carbon fibers. The conventional process of carbon fibers from PAN precursor fiber includes two step; stabilization at low temperature and carbonization at high temperature. Compared to thermal stabilization, the stabilization process by electron beam (E-beam) irradiation is a advanced and brief method. However, a stabilization by E-beam irradiation was required a high dose (over 5,000 kGy) and spend over 1.5 hr (1.14 MeV, 1 mA). In the present work the main goal is exploring a quick stabilization process by cotrolling E-beam currents. The effect of various E-beam currents on stabilization of PAN precursor fiber was studied by gel fraction test, thermo gravimertic analysis (TGA), differential scanning calorimetry (DSC), tensile strength, and scanning electron microscopy (SEM) images.

• Journal of Radiation Industry
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• v.5 no.3
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• pp.249-252
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• 2011

Lignin is one of the natural macromolecules. Every year large amount of lignin arises from the cellulose production as a by-product worldwide. The use of lignin as a precursor to carbonaceous materials has gained interest due to its low cost and high availability. Therefore, we improved the properties of alkali-lignin by exposing to gamma ray in this study. The alkali-lignin is irradiated by Gamma ray irradiation with varying doses. The char yields of alkali-lignin were investigated by increasing up to 50 kGy. The cross-linking and bond scission of alkali-lignin occur simultaneously during gamma ray irradiation. The crosslinking was predominantly accelerated by gamma ray irradiation up to 50 kGy. Bond scission predominantly occurs between 50 and 500 kGy. ESCA analysis indicated that the alcoholic carbon increase up to 50 kGy. Solution viscosity was increased as absorbed dose increased up to 20 kGy. In addition, the aromatic ring was not influenced by irradiation at doses ranging from 20 to 500 kGy as shown in FT-IR results.

• Journal of Radiation Industry
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• v.4 no.3
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• pp.259-263
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• 2010

Carbon fibers are used as a reinforcement material in an epoxy matrix in advanced composites due to their high mechanical strength, rigidity and low specific density. An important aspect of the mechanical properties of composites is associated to the adhesion between the surface of the carbon fiber and the epoxy matrix. This paper aimed to evaluate the effects of electron beam irradiation on the physicochemical properties of carbon fibers to obtain better adhesion properties in resultant composite. Chemical structure and surface elements of carbon fiber were determined by FT-IR, elemental analysis and X-ray photoelectron spectroscopy, which indicated that the oxygen content increased significantly with increasing the radiation dose. Thermal stability of the carbon fibers was studied via the thermalgravimetric analysis. Surface morphology of carbon fiber was analyzed by scanning electron microscope. It was found that the degree of surface roughness was increased by electron beam irradiation.

• Journal of Radiation Industry
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• v.4 no.3
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• pp.265-269
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• 2010

Silicon-based non-oxide ceramic carbide fiber is one of the leading candidate ceramic materials for engineering applications because of its excellent mechanical properties at high temperature and good chemical resistance. In this study, polycarbosilane(PCS) and zirconium butoxide were used as a precursor to prepare polyzirconocarbosilane (PZC) fibers. A polymer solution was prepared by dissolving PCS in zirconium butoxide (50/50 wt%). This solution was heated at $250^{\circ}C$ in a nitrogen atmosphere for 2 hour with stirring, and then dried in a vacuum oven for 48 hour. PZC fibers were fabricated using an electrospinning technique. The fibers were irradiated with an electron beam to induce structural crosslinking. Crosslinked PZC fibers were heat treated at $1,300^{\circ}C$ in a nitrogen atmosphere. The microstructures of PZC fibers were examined by SEM. Chemical structures of PZC fibers were examined by FT-IR and XRD. Thermal stability of PZC fibers was investigated by TGA.

• The Journal of Korean Society for Radiation Therapy
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• v.9 no.1
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• pp.1-7
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• 1997

다량의 방사선에 피폭되는 경우 인체에 해로운 영향을 미치는 것은 틀림이 없으나 미량의 방사선인 경우에는 다량의 방사선인 경우와 다른 효과를 나타내며 심지어 정반대의 영향을 나타내기도 한다고 볼 수 있으며 여러 역학조사에서 이러한 사실이 증명되고 있다. 1991년의 국제방사선방어기구(ICRP) 보고서 및 1994년의 UNSCEAR 보고서는 미량의 방사선에 대한 적응반응을 인정하고 있다. 일부 학자들은 소량의 방사선에 지속적으로 피폭(연간 1 rem)됨으로써 암사망률을 감소시킬 수 있다고 주장하면서 현재의 개념을 수정하여 피폭한계 및 법적 제한 등을 변경하여 환경방사능을 증가시킴으로써 향후 인류의 생활의 질을 향상시켜야 한다고 주장하고 있다.

• Proceedings of the Korean Society of Radiological Science
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• 2001.09a
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• pp.86.1-86.1
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• 2001