• Journal of Institute of Control, Robotics and Systems
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• v.13 no.11
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• pp.1060-1066
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• 2007

When a high-energy ultrasound propagates through a solid body that contains a crack or a delamination, the two faces of the defect do not ordinarily vibrate in unison, and dissipative phenomena such as friction, rubbing and clapping between the faces will convert some of the vibrational energy to heat. By combining this heating effect with infrared imaging, one can detect a subsurface defect in material efficiently. In this paper a detection of the welding defect of thin SUS 304 plates using the UIR (ultrasonic infrared imaging) technology is described. A low frequency (20kHz) ultrasonic transducer was used to infuse the welded thin SUS 304 plates with a short pulse of sound for 280ms. The ultrasonic source has a maximum power of 2kW. The surface temperature of the area under inspection is imaged by a thermal infrared camera that is coupled to a fast frame grabber in a computer. The hot spots, which are a small area around the defect tip and heated up highly, are observed. From the sequence of the thermosonic images, the location of defective or inhomogeneous regions in the welded thin SUS 304 plates can be detected easily.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.6
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• pp.518-524
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• 2001

We report the current limiting properties of superconducting fault current limiters (SFCL). Our SFCL was patterned in a spiral type on a YB $a_2$C $u_3$$O_{7-x}$(YBCO) film deposited using rf sputtering techniques and was coated with a gold shunt layer in order to disperse the heat generated at hot spots in the YBCO film. Current increased up to 13.5 $A_{peak}$ at 60 Hz for the voltage of 13 $V_{peak}$, which is the minimum quench point, and increased up to 17.6 $A_{peak}$ at 60 Hz fo the voltage fo 141.4 $V_{peak}$. The quench completion time was 5 msec at 13 $V_{peak}$ and 4 msec at 141. $V_{peak}$ respectively. we think that this architecture using spiral-type SFCL can be useful for the protection of the power delivery systems from fault currents.s. currents.s.

• Journal of The Korean Astronomical Society
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• v.34 no.1
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• pp.9-15
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• 2001

We present the results of optical differential photometry of five blazars [PKS0219+428 (3C66A), PKS 0235+164 (AO 0235+16), H0414+019, PKS 0851+202 (OJ 287) and QSO 1807+698 (3C 371)] that were observed on 7 nights between November 05, 1997 and December 29, 1998, using the B and the V band filters. We have detected microvariations in four blazars (3C66A, AO 0235+16, H04l4+019, and OJ 287). In addition, the light curve of AO 0235+16 has displayed a mini-flare when the brightness of this source was decreasing. Night-to-night variations have also been detected in 3C66A, H04l4+019, and OJ 287. The results of our observations are discussed in the framework of accretion disk phenomena (magnetic flares or hot spots in accretion disks) and jet phenomena (plasma instabilities in jets).

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.24-24
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• 2003

Research activity in the III-V nitrides materials system has increased markedly in the past several years ever since high-brightness blue light-emitting diodes (LEDs) became commercially available. Despite of excellent optical properties of the GaN, however, inherently poor thermal property of the sapphire used as a substrate material n these devices may lead to thermal degradation of devices, especially during their high power operation. Therefore, dependable thermal analysis and packaging schemes of GaN-based LEDs are necessary for solid lighting applications under high power operation. In this paper, emphasis will be placed upon thermal design of GaN-based LEDs. Thermal measurements of LEDs on chip and packaging scale were performed using the liquid crystal thermographic technology and micro thermocouples for different bias conditions. By a series of optical arrangement, hot spots with specific transition temperatures were obtained with increasing input power. Thermal design of LEDS was made using the finite element method and analytical unit temperature profile approach with optimal boundary conditions. The experimental results were compared to the simulated data and the results agree well enough for the establishment of dependable prediction of thermal behavior in these devices. The paper will present a more detailed understanding of the thermal analysis of the GaN-based blue and white LEDs for high power applications.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.42 no.3
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• pp.58-66
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• 2010

The Annals of beeswax applied-Joseon Dynasty have some serious damages such as cracks, brown, red or black spots, and discolorations by chemical and biological degradation, but others without any beeswax application have still been keeping good quality during over several hundred years. It would be convinced that the beeswax applied in the Annals resulted in these deteriorations. Therefore, in order to focus on the aging mechanism and conservation techniques for the beeswax-applied Annals of Joseon Dynasty, the beeswax applying and dewaxing techniques of Hanji were tried by auto bar coater with a hot plate, and by heat-pressure sensitive extracting treatments. The ageing behaviors of beeswaxed Hanji and dewaxed Hanji were investigated by measuring the changes of physical, optical, morphological, and chemical properties, through accelerated ageing treatment in dry oven at $150^{\circ}C$ during 48 hours. Consequently, the ageing actions of beeswaxed Hanji were even faster than that of Hanji. The optimum dewaxed amounts from beeswaxed Hanji was also obtained in pressure of $40\;kg_f$ under heating conditions.

• Journal of Microbiology and Biotechnology
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• v.5 no.5
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• pp.280-284
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• 1995

Aspergi11us niger F-580, a potent producer of aminopeptidase M inhibitor, was isolated from the brown spots of plant leaves with a pathological trait. The inhibitory activity was found only in the fungal mat formed by surface culture of Aspergi11us niger F-580, but not in the culture supernatant or cell pellet. The inhibitor was purified from the hot water extract of this fungal mat by using chromatographies on Diaion HP-20, DEAE-cellulose, Sephadex G-l0 and YMC-ODS-AQ columns. The purified inhibitor was analyzed by UV, mass, and NMR spectroscopies, and identified as OF494911, which had been isolated as an aminopeptidase B inhibitor from Penicillium rugulosum OF4949

• 한국초전도학회:학술대회논문집
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• v.9
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• pp.214-217
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• 1999

We investigated the quench characteristics of meander line type resistive superconducting fault current limiters based on YBCO thin films grown on 2" diameter LaAlO$_3$ substrates. A gold layer was deposited onto the 0.4 ${\mu}$ m thick YBCO film to disperse the heat generated at hot spots, prior to patterning into 1 mm wide meander lines by photolithography. The limiters were tested with simulated fault currents of various amplitudes. The quench started at 10 A and was completed within 1 msec at the fault current of 65 A$_{peak}$. The dynamic quench characteristics were explained based on the heat conduction within the film and the heat transfer between the film and the surrounding liquid nitrogen. The heat transfer coefficient per unit area was estimated to be 3.0 W/cm$^2$K.

• Journal of Agricultural Extension & Community Development
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• v.22 no.3
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• pp.333-344
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• 2015

The purpose of this study was to assume suitable cultivation areas by items and expectably suitable cultivation areas through coefficient of specialization and spatial concentration analysis, and suggested regional specialized items discovered by this research and regional specialized business management plans & development directions. This study has monitored changing aspects of spatial distribution of suitable cultivation areas in stockbreeding items from 2000 to 2010 by applying methods of location quotient(LQ), a multiple model, and etc, and predicted changing aspects of suitable cultivation areas from 2015 to 2020. As the result of analysis, I found that there were specialized items which were spatially concentrated and that there were hot-spots which were focused on some areas by items. Additionally, there were suitable cultivation areas which remained stable or changed by them. To discover specialized items and to develop businesses, I have suggested that it is necessary to ensure business project's feasibility including the present conditions, circumstances & potential of specialized items, and etc., and to secure business competitiveness including technology exchange, production cost curtailment, business management based on consumer's needs and building systematic data about achievement and etc.

• Journal of Agricultural Extension & Community Development
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• v.27 no.2
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• pp.75-87
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• 2020

The purpose of this study is to investigate the location characteristics of the rice paddy fields and to predict shrinking areas of them. The study area is in South Korea nationwide, and a 300×300m raster level is adopted as a spatial analysis unit. The binary logit model and spatial simulation model are employed for the analyses. As a result, population, industry, climate and nature, and accessibility play a significant role in determining rice paddy fields' locations. It is predicted that the shrinking rate will be high in Gangwon-do, Gyeongsangbuk-do, and Gyeongsangnam-do until 2027. The hot spots are intensively shaped in the inland of Gangwon-do, eastern parts of Gyeonggi-do, and the borders of Gyeongsangnam-do and Jeollabuk-do between Charyeong and Sobaek mountain ranges. Using Gimcheon-si as an example, the study suggests fundamental policy implications for taking advantage of the simulation results from the lens of local agriculture. Several policy measures are proposed for improving management strategies for the rice paddy fields in the long run.

• Genomics & Informatics
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• v.5 no.2
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• pp.68-76
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• 2007

Due to the increasing interest in SNPs and mutational hot spots for disease traits, it is becoming more important to define and understand the relationship between SNPs and their flanking sequences. To study the effects of flanking sequences on SNPs, statistical approaches are necessary to assess bias in SNP data. In this study we mainly applied Markov chains for SNP sequences, particularly those located in intronic regions, and for analysis of in-del data. All of the pertaining sequences showed a significant tendency to generate particular SNP types. Most sequences flanking SNPs had lower complexities than average sequences, and some of them were associated with microsatellites. Moreover, many Alu repeats were found in the flanking sequences. We observed an elevated frequency of single-base-pair repeat-like sequences, mirror repeats, and palindromes in the SNP flanking sequence data. Alu repeats are hypothesized to be associated with C-to-T transition mutations or A-to-I RNA editing. In particular, the in-del data revealed an association between particular changes such as palindromes or mirror repeats. Results indicate that the mechanism of induction of in-del transitions is probably very different from that which is responsible for other SNPs. From a statistical perspective, frequent DNA lesions in some regions probably have effects on the occurrence of SNPs.