Du-Wan Kim

Growth of carbon nanotube field emitters on single strand carbon fiber: a linear electron source

The multi-stage effect has been revisited through growing carbon nanotube field emitters on single strand carbon fiber with a thickness of 11 µm. A prepared linear electron source exhibits a turn-on field as low as 0.4 V µm(-1) and an extremely high field enhancement factor of 19,300, when compared with those results from reference nanotube emitters grown on flat silicone wafer; 3.0 V µm(-1) and 2500, respectively. In addition, we introduce a novel method to grow nanotubes uniformly around the circumference of carbon fibers by using direct resistive heating on the continuously feeding carbon threads. These results open up not only a new path for synthesizing nanocomposites, but also offer an excellent linear electron source for special applications such as backlight units for liquid crystal displays and multi-array x-ray sources.

Effects of genetic variants for the swine FABP3, HMGA1, MC4R, IGF2, and FABP4 genes on fatty acid composition

This study aimed to verify genetic relationships between fatty acid composition (FAC) and genotypes of several genes (FABP3, HMGA1, MC4R, IGF2, and FABP4) using pig breeds. The effects of genetic variations on FAC of the longissimus muscle were statistically significant with additive and dominance effects. The polymorphisms of FABP3 and IGF2 had the largest effects on stearic (C18:0, P=0.009) and γ-linoleic (C18:3n6, P=0.039) acids, respectively, whereas HMGA1 and FABP4 did not show significances. The analysis revealed that MC4R was significantly associated with palmitoleic acid (C16:ln7) and MUFA. Allele frequencies of the genes examined in this analysis were significantly skewed or fixed in the Korean native pig (KNP), whereas the allele frequencies of the crossbreds tended to fall between those of the purebreds except that HMGA1 and FABP4 had approximately the same allele frequencies with Duroc and KNP, respectively. The polymorphisms found in this study could be used as genetic markers in breeding programs to simultaneously change proportions of fatty acids in muscle tissues.

Effect of heat stress on growth performance and physiological changes of pigs in commercial farm

This study investigatedthe effect of heat stress on the performance and blood characteristics in commercial pig farms. A total of 180 growing pigs and 180 finishing pigs were assigned to twotreatments consisting of thermal-neutral period(TNP) and high-temperature period(HTP) with three replications in floor pen, respectively. Feeding trials in the TNP and HTP were individually performedin autumn and summer seasons, respectively. Temperature-humidity index(THI) was calculated by temperature and humidity. Performance and physiological responses were identified per growth stages and feeding trial. Average temperature and THI were 16.8°Cand 61.4 at the TNP, and 25°Cand 74.3 at the HTP, respectively. Growing pigs in HTP exhibited lower BW, ADG and ADFI than in TNP(p<0.01). Similarly, finishing pigs showed lower growth parameters in HTP than in TNP(p<0.01). Lymphocytes and neutrophils of growing pigs were lower in HTP than in TNP(p<0.05). The serum T-PRO and NEFA in finishing pigs were higher in HTP than in TNP(p<0.05). In HTP, finishing pigs had higher cortisol levels than in TNP. Therefore, HTP can negatively influence growth performance and nutritionalmetabolism inpigs. Our results may provide useful information for developing feeding programs and diets to controlheat stress for swine farms.

The commercial huddles of carbon nanotube devices

It has been passed over a decade since the first 5-inch diagonal carbon nanotube (CNT) field emission display was demonstrated. The most of technical issues were solved and the device showed promising performances at that time. However, it is not shown on a market as a new display device although alternative devices like OLED and PDP are on sale. Now scientists and engineers are developing new CNT based devices as like rf amplifiers, THz sources, array e-beam lithography tools, and X-ray sources. The hidden obstacles for the commercialization of CNT devices like the lack of standardization of detailed properties and inspection limitations of process steps should be carefully considered to avoid another failure. The presentation will cover unaddressed but critical huddles for CNT devices commercialization.

Development of backlight and X-ray source based on printed carbon nanotube field emitters

Fully-sealed 46-inch diagonal backlights using printed carbon nanotube field emitters have been developed. The impulse driving together with local dimming in the area as small as 1 cm2 lead to 4 ms moving picture response time with a frame rate 120 Hz and high contrast ratio over 1 000 000:1 in the LCD TV. The technical issues including device architecture and emitter performance are discussed here. In addition, recent results of X-ray source based on the carbon nanotube emitters are presented.