• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2003.05a
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• pp.279-283
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• 2003

As the state of the art in recent years Laser-Arc Hybrid welding is tried actively because of its various economical and technical advantages. In this study, melting tendencies according to the variation of laser-arc distance are investigated in case of YAG laser-TIG Hybrid welding process of AH32 ship structural steel. Nd-YAG laser with a laser beam power of 3KW is used and varied laser-arc distance 0mm to 10mm with fixing the TIG current as l00A. There is certain distance between laser and TIG elecrode to improve welding heat input and also increase the penetration.

• Proceedings of the KWS Conference
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• 2007.11a
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• pp.187-189
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• 2007

• Proceedings of the Korean Magnestics Society Conference
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• 2005.12a
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• pp.20-21
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• 2005

• Journal of Welding and Joining
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• v.25 no.6
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• pp.71-77
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• 2007

Until now, many researches on laser-arc hybrid welding processes have been conducted mainly for high power CW laser and high direct current arc to weld the thick steel plates for shipbuilding. Recently, however the usage of thin steel plates, which tend to be deformed easily by thermal energy, is been increasing because of demand of light structure such as car body in the automobile industry. Accordingly, heat sources having relatively low heat input such as pulsed laser, dip-transfer DC GMA and pulsed GMA seem to be applied more increasingly and the study about those heat sources is needed more intensively. Any heat source mentioned above can not stand alone without weld defects at a relatively high welding speed for increasing the welding productivity. This is main reason to apply the hybrid welding process which uses pulsed laser and low-heat-input GMA heat sources simultaneously to weld the thin steel plate. In this study, parameters of pulsed laser and dip-transfer DC GMA welding are studied firstly through preliminary experiments, and then analyzed in the viewpoint of their physical phenomena. Before conducting the hybrid welding, a pulse control technique is developed based on the parallel port communication and Visual C++ 6.0. Owing to development of this technique, interactions of laser and arc pulses can be controlled consistently. Using the pulse control technique, the hybrid welding is conducted and then its interactive welding phenomenon is analyzed.

• Journal of Sericultural and Entomological Science
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• v.48 no.1
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• pp.16-20
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• 2006

To shorten the labor cost for the production of the fungus, Paecilomyces tenuipies, uncocooning mutant hybrid silkworms as a host was used. The yield of P. tenuipies was reduced when Nd (uncocooning mutant) was used as a host because Nd was smaller than the hybrid Baegokjam that has been used as a typical host. To increase the host weight, Nd was crossed with Jam l23 or Jam 124, and resulted in not only greater weighter but also higher yield of P. tenuipies. The optimum temperature for rearing Nd hybrid silkworms was $3^{\circ}C$ higher than standard temperature of rearing silkworms to increase the naked pupation rate. The optimum time for the infection of P. tenuipies was 12 h at $28.5^{\circ}C$ and 95% R.H., when $1{\times}10^7spores/ml$ of P. tenuipies were sprayed on the surface of the silkworm. The conditions were applicable to both spring-rearing and autumn-rearing.

• Journal of The Korean Society of Grassland and Forage Science
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• v.25 no.1
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• pp.23-32
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• 2005

This experiment was carried out to determine on the growth characteristics, yield and palatability in mono-cropping(T1; sorghum $\times$ sudagrass hybrid, T2; soybean) and inter-cropping[T3; sorghum $\times$ sudagrass hybrid(1) + soybean(2)]. The results obtained are summarizes follows; In plant length. leaf length, leaf width and stem diameter of sorghum $\times$ sudagrass hybrid(SSH). T3(1) was lower than T1 at 1st cutting time. But in 2nd and 3rd cutting time. T3(1) was higher than T1 Stem diameter of T2 was higher than soybean of T3(2). but plant length, leaf length and leaf width of T2 were higher than T3(1). The leaf ratio of SSH in T3(1) was higher than T1 in the first cutting time, but T3(1) was higher than T1 at 2nd and 3rd cutting time. The number of tiller of T1 was higher than SSH of T3(1) at 1st cutting time, but T3(1) was higher than T1 at 2nd and 3rd cutting time. Dead stubble rate of SSH in T3(1) showed a little lower value than T1. Dry matter and fresh yield of T1 was higher than T2 and T3. But protein yield of T3 was higher than T1 The palatability of 1st cutting time was 100.0. 76.8 and $18.5\%$ on T2, T3 and T1, respectively.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.38 no.5
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• pp.466-476
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• 1993

Field experiment was carried out to study the new and old leaf development and photosynthesis of sorghum-sudangrass hybrid 855F, pearl millet Suwon No.6 and barnyard millet in cutting and non-cutting plots from the 2nd cutting day(September, 17th). Leaf regrowth of sorghum-sudangrass hybrid and pearl millet begun after the 2nd cutting day, except barnyard millet. Photosynthetic rate of new leaf blades in cutting plots reached to higher level than old leaf at 12th to 20th day after cutting(DAC). Stomatal density of leaf blade of each crop in non-cutting plot was observed higher pearl millet and sorghum-sudangrass hybrid than barnyard millet. New leaf blade of each crop in cutting plot was showed complete development in stomata size, form and vascular bundles in 12th DAC. Non-structural carbohydrates(NSC) contents of stembase in sorghum-sudan hybrid which had 17 %, the highest among three forages decreased daily into 8th DAC and begun to increase from 20th DAC. But, those of pearl millet and barnyard millet in cutting plots were about 10 % at cutting day and inclined to decrease continuously into the 20th DAC and reached about 3～4% in 32nd DAC. These results showed that regrowth energy of sorghum-sudangrass hybrid was mainly dependent on non-structural carbohydrates of stembase until 12th DAC, but pearl millet had active lower leaves supported its regrowth by concurrent photosynthesis. As barnyard millet which did not reserve enough NSC, its regrowth fail to survive under low temperature. Also, late regrowth of rest two forage crops was delayed with decreasing daily temperature after mid-September.

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.169-175
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• 2002

World demand for natural gas has generated the need for many new land transmission pipelines to be installed in the next decade or so. Although mechanized gas metal arc welding is well developed, there are opportunities for cost savings by using alternative welding processes. Hybrid Nd:YAG laser - gas metal arc welding enables fibre optic delivery of the laser energy to a robotic welding head to be combined with the addition of extra energy and a consumable to produce good quality, deep penetration welds in a single pass. The present paper describes initial procedure development to optimize the laser and gas metal arc welding parameters for making joints in pipeline steel. Satisfactory joint quality was obtained and it is intended to develop the process to prototype field trials.

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.162-168
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• 2002

Hybrid Welding means the coupling of the energy of two different energy sources in a common process zone. This paper describes prospects in laser-arc-hybrid-welding. Different kinds of lasers ($CO_2$ laser and Nd:YAG laser) and arc processes (TIG, Plasma and GMA) are considered.

• Journal of Powder Materials
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• v.15 no.4
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• pp.263-270
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• 2008