• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.17 no.12
• /
• pp.1264-1270
• /
• 2004

A fast switching thyristor with a superior trade-off property between the on-state voltage drop and the turn-off time could be fabricated by the proton irradiation method. After making symmetric thyristor dies with a voltage rating of 1,600 V from 350 $\mu$m thickness of 60 $\Omega$ㆍcm NTD-Si wafer and 200 $\mu$m width of n-base drift layer, the local carrier lifetime control by the proton irradiation was performed with help of the HI-13 tandem accelerator in China. The thyristor samples irradiated with 4.7 MeV proton beam showed a superior trade-off relationship of $V_{TM}$ = 1.55 V and $t_{q}$ = 15 $\mu$s attributed to a very narrow layer of short carrier lifetime(～1 $\mu$s) in the middle of its n-base drift region. To explain the small increase of $V_{TM}$ , we will introduce the effect of carrier compensation at the low carrier lifetime region by the diffusion current.ffusion current.t.

• KSBB Journal
• /
• v.29 no.4
• /
• pp.297-302
• /
• 2014

The autoclaving assisted by an irradiation pretreatment method was developed without toxic chemicals to produce fermentable sugars for their conversion to bioethanol. In the first step, electron beam irradiation (EBI) of rice straw was performed at various doses. The electron beam-irradiated rice straw was then autoclaved with DI water at $120^{\circ}C$ for 1 h. A total sugar yield of 81% was obtained from 300 kGy electron beam-irradiated rice straw after 72 h of enzymatic hydrolysis by Cellulase 1.5L (70 FPU/mL) and Novozyme-188 (40 CbU/mL). Also, the removal of hemicellulose and lignin was 32.0% and 32.5%, respectively. This result indicates that the environmentally-friendly pretreatment method of rice straw by an electron beam irradiation could be applied for bioethanol production in plant.

• Journal of the Korean Solar Energy Society
• /
• v.39 no.4
• /
• pp.11-24
• /
• 2019

The total solar irradiation on horizontal surfaces is separated into the beam and diffuses components. Although horizontal global irradiance is a commonly measured parameter for many sites, horizontal diffuse irradiance is not so readily obtainable. For such sites that measure global irradiation alone, a simple but reasonably accurate method is required to estimate diffuse irradiance from its global counterpart. This study investigates the applicability of correlation coefficients models correlating hourly diffuse and beam fraction and hourly clearness index in Daejeon. The three diffuse to global correlation coefficients models (Orgill and Holland model, CIBSE Guide J model, and Erbs et al. model) are selected and the three modified beam to global correlation coefficients models are generated. MBE, RMSE, r-squared of Daejeon and Daejeon boundary site-fitted models are compared with the case of original coefficients. The comparison result shows that the beam and diffuse to global solar irradiation correlation coefficients models with boundary site-fitted coefficients are best suitable for Daejeon. Further researches will be conducted to find the boundary site-fitting method using measured data of other cities and correlation coefficients models using solar altitude, cloud cover, and sunshine duration.

• Nuclear Engineering and Technology
• /
• v.51 no.1
• /
• pp.221-227
• /
• 2019

One of the important requirements for the application of reduced activation ferritic/martensitic steel is to retain proper mechanical properties in irradiation and high temperature conditions. In order to simulate the impact toughness with the effect of temperature and irradiation, a simulation model based on energy balance method consisted of crack initiation, plastic propagation and cleavage propagation stages was established. The effect of temperature on impact toughness was analyzed by the model and the trend of the simulation results was basicly consistent with the previous experimental results of CLAM steels. The load-displacement curve was simulated to express the low temperature ductile-brittle transition. The effect of grain size and inclusion was analyzed by the model, which was consistent with classical experiment results. The transgranular-intergranular transformation in brittle materials was also simulated.

• Bulletin of the Korean Chemical Society
• /
• v.26 no.11
• /
• pp.1701-1705
• /
• 2005

We have established an efficient method for the synthesis of the arylpiperazine derivatives in which the acylation of 2-aminopyridine, the coupling reaction of the acyl compound with piperazines, and reduction of the arylpiperazines were performed under a microwave irradiation (300 W) to afford the corresponding target compounds in quantitative yields. In all cases, the reaction times were remarkably reduced when compared with those of the conventional method.

• Transactions of the Korean Society of Pressure Vessels and Piping
• /
• v.14 no.1
• /
• pp.1-7
• /
• 2018

Materials in nuclear power plants can be embrittled by neutron irradiation. According to existing studies, the effect of the material property by irradiation embrittlement can be approximately simulated by cold working (pre-strain). In this study, finite element damage analysis method using the stress-modified fracture strain model is proposed to predict J-Resistance curves of irradiated SUS316 stainless steel. Experimental data of pre-strained SUS316 stainless steel material are obtained from literature and the damage model is determined by simulating the tensile and fracture toughness tests. In order to consider damage caused by the pre-strain, a pre-strain constant is newly introduced. Experimental J-Resistance curves for various degrees of pre-strain are well predicted.

• The Plant Pathology Journal
• /
• v.26 no.3
• /
• pp.286-288
• /
• 2010

Plant tissue homogenization using a mortar or mechanical equipment has been the preferred method for obtaining high yields of total RNA; this method, however, is both time-consuming and expensive. Additionally, homogenization may generate excessive endogenous RNases, polyphenolics, and other substances that reduce the quality and quantity of RNA. In this study, we describe the microwave irradiation-assisted RNA extraction (MIRE) technique which, without tissue disruption and homogenization, allows for the cost-effective and rapid generation of intact RNA from apple cane shavings and the reliable detection of apple virus by RT-PCR.

• Environmental Engineering Research
• /
• v.25 no.4
• /
• pp.470-478
• /
• 2020

Spent coffee grounds (SCG), the residue after brewing coffee beverage, is a promising biodiesel feedstock due to its high oil contents (15-20%). However, SCG should be pretreated to reduce the high free fatty acid content, which hampers transesterification reaction. To overcome this, we explored a direct transesterification reaction of SCG using ultrasound irradiation and identified the optimal sonication parameters. A high fatty acid methyl ester (FAME) content, up to 97.2%, could be achieved with ultrasound amplitude of 99.2 ㎛, irradiation time of 10 min, and methanol to oil ratio of 7:1 in the presence of potassium hydroxide concentration of 1.25 wt.%. In addition, we demonstrated that ultrasound irradiation is an efficient method to produce biodiesel from untreated SCG in a short time with less energy than the conventional mechanical stirring method. The physical and chemical properties of the SCG biodiesel met the requirements for an alternative fuel to the current commercial biodiesel.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.47 no.6
• /
• pp.81-88
• /
• 2015

The molecular weight (MW) and crystallinity of cotton linter need to be controlled to be dissolved well in N-methylmorpholine N-oxide (NMMO) solvent for manufacturing regenerated fibers of clothing fabrics. Electron beam irradiation or sulfuric acid pre-treatment followed by alkaline peroxide bleaching has been used to control MW effectively and to improve brightness of cotton linter. Auto-hydrolysis of cotton linter without electron beam irradiation or chemical pre-treatment was found to be effective as an alternative pre-treatment method. Removal of metal ions, that hampered dissolution of cotton linter by NMMO, was also investigated when the auto-hydrolysis was accompanied with ionic polymers and chelating agent.

• Preventive Nutrition and Food Science
• /
• v.3 no.2
• /
• pp.203-209
• /
• 1998

The development of methods for the identification of irradiated foods helps enforce national and international regulations on labelling to ensure the consumer's free choice to buy irradiated or unirradiated foods. and the availabilityof such methods may assist the promotion of international trade in irradiated food products and help prevent abuse of the technology. A number of approaches to determine the physical , chemical, microbiological and biological changes that occur in foods treated with ionizing radiation have been studied. However no single method is universally applicable. Among physical measurements, the leading methods of indentification are electron spin resonance (ESR) spectroscopy and thermoluminescence(TL). ESR is an established non-destructive method for the analysis of free radicals from their traps and TL is the emission of light from irradiated mineral extracts by heating. Viscosity of carbohydrate polymers by causing chain breaks by irradiation, measuring the impedance of potatoes and detection of gases produced radiolytically are promising techniques for identification purposes. Irradiated water-containing foods show significant supercooling when monitored with a differential scanning calorimeter (DSC), which can be applied to identifying irradiated ones.