• Journal of Plant Biotechnology
• /
• v.3 no.3
• /
• pp.151-157
• /
• 2001

In order to breed barley lines with reduced viscosity of wort, a fractured starch mutant of naked barley cultivar, Nubet, was obtained from the M2 seeds mutated by the diethyl sulfate treatment. Seeds of this fractured starch mutant were opaque and the endosperm consists of angular, irregular and fractured starch. The mutant was caused by single recessive mutation and assigned by the symbol fra. The gene was located on chromosome 4, distal in long arm by linkage recombinations using translocation homozygote lethal test set. The linkage value between the fractured starch mutant and 72-4a, 72-4d were 26.0$\pm$4.9, 34.2$\pm$3.1 percent respectively. In addition to the reduced seed size, fewer kernels per spike and higher tillering ability, lower $\beta$-glucan viscosity and higher lysine content of the grain were associated with this mutant. $\beta$-glucan viscosity of the Nubet grains increased from 3 weeks after anthesis to matury and most of the viscose substances appeared to be stored in the middle of the endosperm tissue. Since the mutant grains showed better milling property as compared to Nubet, it can be used as breeding resources to develope new barley cultivars for maltins and milling purpose.

• Transactions of the Korean Society of Pressure Vessels and Piping
• /
• v.14 no.1
• /
• pp.58-65
• /
• 2018

The purpose of this study is to develop a Half Nozzle Repair(HNR) process to prevent the leakage from welds on small bore piping in Reactor Coolant System. The Codes & Standards of tempered bead and design requirements of J-Groove welds are reviewed. Automatic machine GTAW welding and machining equipments are developed to perform HNR process. Single pass welding and overlay welding equipments are conducted in order to obtain the optimal temper bead welding process parameters with Alloy 52M filler wire. Coarse grain heat affected zone(CGHAZ) is formed by rapid cooling rate in heat affected zone after welding. Accordingly, a proper temper bead technique is required to reduce CGHAZ in 1-Layer of welds by 2- and 3-Layers. Mock-up tests show that the developed HNR process is possible to meet ASME Code & Standard requirements without any defect.

• Advances in materials Research
• /
• v.1 no.3
• /
• pp.205-219
• /
• 2012

Co-Re alloy development is prompted by the search for new materials for future gas turbines which can be used at temperatures considerably higher than the present day single crystal Ni-based superalloys. The Co-Re based alloys are designed to have very high melting range. Although Co-alloys are used in gas turbine applications today, the Co-Re system was never exploited for structural applications and basic knowledge on the system is lacking. The alloy development strategy therefore is based on studying alloying additions on simple model alloy compositions of ternary and quaternary base. Various strengthening possibilities have been explored and precipitation hardening through fine dispersion of MC type carbides was found to be a promising route. In the early stages of the development we are mainly dealing with polycrystalline alloys and therefore the grain boundary embrittlement needed to be addressed and boron addition was considered for improving the ductility. In this paper recent results on the effect of boron on the strength and ductility and the stability of the fine structure of the strengthening TaC precipitates are presented. In the beginning the alloy development strategy is briefly discussed.

• The Transactions of the Korea Information Processing Society
• /
• v.4 no.6
• /
• pp.1481-1494
• /
• 1997

In hard real-time systems, a timing fault may yield catastrophic results. Dynamic scheduling provides the flexibility to compensate for unexpected events at runtime; however, scheduling overhead at runtime is relatively large, constraining both the accuracy of the timing and the complexity of the scheduling analysis. In contrast, static scheduling need not have any runtime overhead. Thus, it has the potential to guarantee the precise time at which each instruction implementing a control action will execute. This paper presents a new approach to the problem of analyzing high-level language code, augmented by arbitrary before and after timing constraints, to provide a valid static schedule. Our technique is based on instruction-level complier code scheduling and timing analysis, and can ensure the timing of control operations to within a single instruction clock cycle. Because the search space for a valid static schedule is very large, a novel adaptive genetic search algorithm was developed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1995.11a
• /
• pp.213-216
• /
• 1995

Strontium niobate, $Sr_2Nb_2O_{7}$ was prepared by the molten stilt synthesis (MSS) and the chemical coprecipitation method (CCP). Single phase $Sr_2Nb_2O_{7}$ was obtained by MSS and CCP at $750^{\circ}C$ and $800^{\circ}C$, respectively. An intermediate phase of composition, $Sr_{5}Nb_4O_{15}$, appeared at $700^{\circ}C$ when CCP method was employed. The resulting powder was observed to have finer particles and more uniform distribution of particle sizes, as compared to those obtained through the conventional method. Such powder characteristics allowed the use of a much lower sintering temperature of $1400^{\circ}C$. Grain-orientation along (0k0) direction, which is advantageous for improving dielectric properties, was also observed. The sintering characteristics and the dielectric properties prepared by MSS and CCP, were better than those by the conventional method.

• The Korean Journal of Ceramics
• /
• v.5 no.3
• /
• pp.224-229
• /
• 1999

The preparation and toughening of SiC-AIN solid solution from powder mixtures of $\beta$-SiC, AIN and $\alpha$-SiC by hot-pressing were studied in the 1870 to $2030^{\circ}C$ temperature range. The reaction of AIN and $\beta$-SiC(3C) powders causing transformation to the 2H(wurtzite) structure appeared to depend on hot-pressing temperatures and an additive of $\alpha$-SiC. For the composition of 49wt% SiC with 2 wt% $\alpha$-SiC and 47.5 wt% AIN47.5wt% SiC with 5 wt % $\alpha$-SiC at 203$0^{\circ}C$ for 1 h, th complete solid solutions with a single phase of 2H could be obtained. The appreciable amount of $\alpha$-SiC could develop the columnar inter-grains of 4H phase and the stable 2H phase with the relatively uniform composition and grain size distributions. The effect of $\alpha$-SiC on the phases present and compositional microstructures with columnar inter-grains was invetigated using X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The fracture toughness and Vickers hardness of the hot-pressed solid solutions wre examined by the indentation-fracture-test method.

• Journal of the Korean Ceramic Society
• /
• v.44 no.10
• /
• pp.537-541
• /
• 2007

Microwave dielectric properties of $0.95 Ca_{0.85}Nd_{0.1}TiO_3-0.05LnAlO_3$ (Ln=Sm, DH, Er) were investigated as a function of sintering temperature and lanthanide ion type. A single perovskite phase with an orthorhombic structure was obtained throughout the entire range of composition. The dielectric constant (K) was dependent upon the dielectric polarizabilities and the B-site bond valence in the $ABO_3$ perovskite structure. The quality factor (Qf) of the specimens with $ErAlO_3$ was smaller than those with $SmAlO_3\;and/or\;DyAlO_3$ due to the smaller grain size. The temperature coefficient of resonant frequency (TCF) could be controlled from $107.28ppm/^{\circ}C$ at Ln=Sm to $87.23ppm/^{\circ}C$ at Ln=Er due to the changes of B-site bond valence in the $ABO_3$ perovskite structure.

• Journal of Mechanical Science and Technology
• /
• v.20 no.7
• /
• pp.1077-1088
• /
• 2006

This paper describes a numerical investigation on the performance deteriorations of a low speed, single-stage axial turbine due to use of rough blades. Numerical calculations have been carried out with a commercial CFD code, CFX-Tascflow, by using a modified wall function to implement rough surfaces on the stator vane and rotor blade. To assess the stage performance variations corresponding to 5 equivalent sand-grain roughness heights from a transition ally rough regime to a fully rough regime, stage work coefficient and total to static efficiency were chosen. Numerical results showed that both work coefficient and stage efficiency reduced as roughness height increased. Higher surface roughness induced higher blade loading both on the stator and rotor which in turn resulted in higher deviation angles and corresponding work coefficient reductions. Although, deviation angle changes were small, a simple sensitivity analysis suggested that their contributions on work coefficient reductions were substantial. Higher profile loss coefficients were predicted by higher roughness heights, especially on the suction surface of the stator and rotor. Furthermore sensitivity analysis similar to the above, suggested that additional profile loss generations due to roughness were accountable for efficiency reductions.

• Proceedings of the Korean Society of Crop Science Conference
• /
• 2017.06a
• /
• pp.11-11
• /
• 2017

The most drought resistant among the five most important cereal crops, and a key dual-use (grain and biomass) crop in regions containing some of the world's most degraded soils, sorghum has inherent climate resilience that is likely to become more important under environmental conditions that are projected by many climate change models. The importance of sorghum might be further elevated by the development of productive genotypes that increase the extent and duration of soil cover beyond those of conventional annual crops, mitigating or even reversing losses of ecological capital through multiple crops from single plantings. Rich genetic and genomic resources have been developed to link Sorghum phenotypic diversity to its molecular basis, and in particular the genus has become a model for dissecting the molecular control of perenniality. Nature has made Sorghum perennial at least twice, and crosses between wild perennials and cultivated sorghums show the feasibility of developing genotypes with varying degrees of investment in perenniality while still providing harvestable food, feed, sugar and/or cellulose. Genetic analysis of progeny from these crosses is revealing the hereditary basis of traits related to ratooning and perenniality and providing diagnostic DNA markers. One perennial Sorghum species has adapted to continents and latitudes far beyond the reach of its progenitors, surviving stresses year after year that are only periodically experienced by conventional (annual) sorghum, and may also harbor novel alleles that may mitigate production challenges in conventional annual sorghums.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.10 no.3
• /
• pp.205-210
• /
• 2000

Lead titanate thin films were fabricated on Si(100) wafer and ITO-coated glass substrates by metal organic chemical vapor deposition using ultrasonic spraying. When the ratio (Ti/Pb) of starting materials was 1.2, the films deposited on Si wafer had a single perovskite phase. The films deposited on ITO-coated glass had higher growth rate than that on Si wafer. As deposition temperature was increased from $530^{\circ}C$ to $570^{\circ}C$, dielectric constant was increased due to the increase of crystallinity and grain size. At $570^{\circ}C$, dielectric constant and dielectric loss of the films were 205 and 0.016, respectively. When the deposition temperature is higher than $600^{\circ}C$, dielectric constant was decreased.