• Journal of the Korean Society of Safety
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• v.18 no.4
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• pp.64-70
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• 2003

The thermal properties of chloroprene rubber (CR) with $^{60}Co\;{\gamma}$-ray irradiation has been investigated. The prepared CR was irradiated up to 1000kGy radiation dose by $^{60}Co\;{\gamma}$-ray and the radiation degradation of CR was investigated by thermogravimetric analysis and differential acanning calorimetry. Dynamic mechanical properties measurement and FT-IR observation are carried out as well. From these analyses results, the glass transition temperature($T_g$), decomposition onset temperature(DOT), oxidative induction time(OIT), the peak temperature of loss modulus and mechanical tan ${\delta}$ values were compared for the radiation degradation level of CR. The tendency between $T_g$ and peak temperature of loss modulus and mechanical tan ${\delta}$ agreed well with radiation doses. Decomposition temperature, OIT and DOT showed the same tendencies as increasing radiation doses. It was verified that these analyses are available to estimate the degradation level of CR.

• 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.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.6 no.2
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• pp.125-128
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• 2012

Kenaf (Hibiscuc cannabinus L.) is a renewable resource for industry and kenaf lignin is syringyl-guaiacyl lignin. The electron beam irradiated on kenaf core various doses range from 200 to 1,000 kGy to improve delignification. The yield of lignin, which is 2.53 g from 10 g of electron beam irradiated kenaf core. A comparison extracted lignin between from native kenaf core and electron beam irradiated kenaf core was then studied through chemical structure and bonding property by a Fourier transform infrared spectroscopy (FT-IR). Thermal stability of the extracted-purified lignin was performed via differential scanning calorimetry (DSC). These results were explained that electron beam irradiation increased performance of extracting efficiency.

• Journal of Radiation Industry
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• v.7 no.2_3
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• pp.149-154
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• 2013

In this study, the simple preparation of poly(sodium 4-styrenesulfonate) (PSS)-patterned substrate via a selective ion irradiation was investigated to manipulate cell adhesion. PSS thin films spin-coated onto the hydrophobic polystyrene (PS) was patterned through masked 150 keV proton irradiation followed by developing with deionized water. The characteristics of the resulting PSS-patterned surfaces were investigated by using microscope, surface profiler, FT-IR, XPS, and contact angle analyzer. These analytical results revealed that the resolved $100{\mu}m$ PSS patterns were formed on the hydrophobic PS surface above the fluence of $1{\times}10^{15}ions\;cm^{-2}$ and the chemical structure, composition, and wettability of the PSS patterns were dependant on a fluence. Moreover, the results of the in-vitro cell culture and proliferation assay exhibited that H1299 cells preferentially adhered and proliferated onto the more hydrophilic PSS part of the PSS-patterned PS and the well-aligned cell patterns was formed on the PSS-patterned PS particularly at the fluence of $1{\times}10^{15}ions\;cm^{-2}$.

• 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.

• Journal of Radiation Industry
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• v.8 no.1
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• pp.49-52
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• 2014

Kenaf fibers have excellent properties and possess the potential to be outstanding reinforcing fillers in cement. The grafting of poly(ethylene glycol) methacrylate (PEGMA) to the kenaf fibers is important in improving the compatibility between the fibers and the cement. PEGMA was grafted onto kenaf fibers using gamma-ray radiation. The radiation dose ranged from 20 to 60 kGy, and the dose rate was $10kGy\;h^{-1}$. The degree of grafting increased with increased radiation doses. FT-IR analysis revealed an increase in PEGMA content after gamma-ray radiation induced grafting, further evincing the attachment of PEGMA to the kenaf fibers. The mechanical properties of the gamma-ray grafted kenaf fiber/cement composites were superior to those of the ungrafted kenaf fiber/cement specimens.

• Korean Journal of Soil Science and Fertilizer
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• v.5 no.2
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• pp.75-82
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• 1972

The proposed hypothesis that the effects of climatic factors during ripening period (from 10 days before heading to 30 days after heading) on ripened grain ratio are equal on the level of canopy and on the level of tiller in that canopy of rice plant appeared to be agreeable. The followings were found according to the analysis of ripening structure at tiller level. 1. The optimum ripening temperature (mean air temperature during ripening period) was $21^{\circ}C$ for Jinheung and $22^{\circ}C$ for IR667-Suwon 214. 2. The minimum mean solar radiation ($cal\;cm^{-2}\;day^{-1}$) of ripening period was not greater than 240 for Jinheung and greater than 270 for IR 667-Suwon 214. 3. The ripened grain ratio was not different from main culm to first tillers of second order of main culm in Jinheung but greatly decreased from 4th tiller of first order of main culm in IR667 and the number of grain per main culm was greater in IR667 than in Jinheung indicating that yield of IR667 could be increased by increasing the number of main culm. 4. The last heading date insuring optimum ripening period appeared to be 25th in August for Jinheung and 30th in August for IR667 in Suweon.

• Current Industrial and Technological Trends in Aerospace
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• v.8 no.2
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• pp.65-75
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• 2010

In 2014, Japan is scheduled to launch GCOM(Global Change Observation Mission)-C for the global change observation mission, where SGLI(Second-generation Global Imager) is planned for optical multi-channel observation ofa radiation budget and a carbon cycle. Depending on the spectral channels, SGLI consists ofS GLI-VNR(Visible Near IR) and SGLI-IRS(IR Scanning). Their main design schemes are mostly based upon those ofthe previous instruments ever developed in Japan, which is intended to reduce the development risk for the advanced performance. Accordingly, for the better understanding ofSG LI, the paper reviews the history oft he Japanese optical payloads from two different views: VNR and IR. Through the review, a comparison among the Japanese optical instruments is made to distinguish the development trend toward SGLI ofGC OM-C.

• Journal of the Korea Institute of Military Science and Technology
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• v.13 no.3
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• pp.470-477
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• 2010

This paper is a part of developing a program that predicts the surface temperature and the IR images of ground objects by considering solar irradiation and atmospheric convection. The thermal modeling is essential for identifying objects on the scenes obtained from the remote sensing. And the temperature distribution on the objects is necessary to obtain their infrared images in contrast to the background. We considered the composite heat transfer modes including conduction, convection and spectral solar radiation incident on the objects within a scene to calculate the surface temperature distribution. The surface temperatures obtained by using the S/W developed in this study(Silhouette) and a commercial S/W(SE-Workbench-IR) are computed and compared each other. Results obtained by using the S/W developed in this study(Silhouette) show fairly good agreement with those obtained by the SE-Workbench-IR.