• Metals and materials international
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• v.24 no.6
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• pp.1346-1358
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• 2018

A novel additive manufacturing method with TIG-MIG hybrid heat source was applied for fabricating 5356 aluminum alloy component. In this paper the microstructure evolution, mechanical properties and fracture morphologies of both as-deposited and heat-treated component were investigated, and how these were affected by different heat-treated temperature. The as-deposited microstructure showed dominant equiaxed grains with second phase, and the size of them is coarse in the bottom region, medium in the middle region and fine in the top region owing to different thermal cycling conditions. Compared with as-deposited microstructure, the size of grain becomes large and second phases gradually dissolve in the matrix as heat-treated temperature increase. Different microstructures determine the mechanical properties of component. Results show that average ultimate tensile strength enhances from 226 to 270 MPa and average microhardness increases from 64.2 to 75.3 HV0.1 but ductility decreases from 33 to 6.5% with heat-treated temperature increasing. For all components, the tensile properties are almost the same in the vertical direction (Z) and horizontal direction (Y) due to equiaxed grains, which exhibits isotropy, and the mechanisms of these are analyzed in detailed. In general, the results demonstrate that hybrid arc heat source has the potential to fabricate aluminum alloy component.

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.94-100
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• 2002

During the last years, great progress has been made in the fields of welding power sources and filler materials for the MIG-welding of magnesium alloys. This advice resulted in a better welding process, md, therefore, in highly improved welding results. Furthermore the gap between short-circuiting- and spray-arc-trunsfer could be closed by the triggered short-circuiting- and the short-circuiting-arc with pulse overlay. A crucial contribution to the welding process is the energy input into the filler material. Many problems result from the physical properties of magnesium, for instance its narrow interval between melting point 600$^{\circ}C$ and vaporization point 1100$^{\circ}C$. The energy input into the filler material has to be regulated in such a way that the wire will melt but not vaporize. For th is reason, special characteristics of power sources hue been examined and optimized with the help of high-speed-photographs of the welding process with particular consideration of the drop detachment. An important improvement of the weld seam profile has been achieved by using filler material of only 1.2 mm in diameter. The experiments hue been made with 2.5 mm thick extruded profiles of AZ31 and AZ6l. The results of tensile testing showed strength values of 80 to 100% of the base metal. B ending angles up to 60$^{\circ}$ have been reached. The fatigue strength under reversed bending of the examined magnesium alloys after welding reaches 50% of the strength of the base metal. When the seam reinforcement is ground of the fatigue strength can be raised up to 75% of the base metal.

• Journal of Welding and Joining
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• v.32 no.1
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• pp.28-33
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• 2014

In this paper, I-butt welding with 6mm thickness using Plasma-GMA welding was carried out. And weld characteristics of the Al-5083 aluminium alloy for Plasma-GMA hybrid welding was evaluated. The orthogonal experimental design was used to investigate the influence of plasma-MIG welding parameters such as plasma current, wire feeding rate, MIG-welding voltage and welding speed on the weld bead geometry and tensile strength using the ANOVA(Analysis of Variation). Then we conducted evaluation of contribution for process parameters. ANOVA results show that bead dimensions are affected by wire feeding speed, welding voltage and welding speed and tensile strength is mainly affected by welding speed and plasma arc current. Tensile strength was decreased by rise in plasma welding current because GMA welding current was decreased by plasma arc.

• The Korea Journal of Herbology
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• v.22 no.4
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• pp.233-238
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• 2007

Objectives : Scutellariae Radix (Hwanggeum in Korean) is the root of Scutellaria baicalensis Georgi. Scutellariae Radix is well known to be used as a medicine for common cold, upper respiratory infections, and to strengthen and regulate the immune system and anemia etc. Little is understood about the roles of Scutellariae Radix in the cytokine and chemokine secretion by immune cells. This study was designed to find out the effects of Scutellariae Radix on the cytokine and chemokine secretion in human mast cells (HMC-1). Methods : We treated hwanggeum according to consistency on HMC-1 and measured cytokines and chemokines levels using flow cytometry CBA system. Results : In hwanggeum treated group, the expression of interferon-inducible protein 10 (IP-10), monocyte chemoattractant protein-1 (MCP-1), chemokine (C-X-C motif) ligand 9 (CXCL9, MIG), interleukin 8 (IL-8), interleukin 2 (IL-2), interleukin 4 (IL-4), interleukin 5 (IL-5), interleukin 10 (IL-10), and interferon ${\gamma}$ (IFN-${\gamma}$) were decreased significantly. Conclusion : These results suggest that hwanggeum may support some of immune diseases by means of amiliorating some chemokines or cytokines such as IP-10, MCP-1, MIG, IL-8, IL-2, IL-4, IL-5, IL-10, and IFN-${\gamma}$.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.6
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• pp.26-33
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• 2008

This paper presents a new full-bridge soft switching PWM DC-DC converter circuit topology that adding one switcher, one lossless snubber quasi-resonance capacity to power source for general welding machine This full-bridge soft switching DC-DC convoter· topology can applicable 600[V] switching device (IGBT)incase of AC 400[V] common power source because the voltage of active switcher is 1/2 of DC bus line voltage. And low voltage hight current out)ut that first coil current is smaller than second coil current in high frequency transformer can be obtained with decreasing path loss in conventional DC bus line switcher. As it operate ZCS/ZVS in full range, high frequency, high efficiency and high output are implemented at low voltage and high DC current switching power supplies. All of this items are got from simulation and the result of experiment. If make up for the weak points of this proposed circuit, it will be used more easily for next generation TIG, MIG and MAG type of arc-welding machine.

• Proceedings of the Korean Magnestics Society Conference
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• 2002.12a
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• pp.222-223
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• 2002

자기헤드에서 사용되는 연자성 박막에서 요구되는 특성 중 가장 중요한 것은 우수한 연자기 특성의 화보와 헤드제조공정에서 필수적인 유리접합공정(MIG 헤드의 경우 약 500~600 $^{\circ}C$의 열처리) 이후에도 연자기 특성이 유지되는 내열성이다. 이러한 관점에서 우수한 연자기 특성과 내열성을 동시에 보유하는 연자성 박막재료에 대한 연구가 활발히 진행되어 Fe-TM(Hf, Zr. Ta 등)-(B. C, N) 계 등이 보고되었다[1-4]. (중략)

• Genomics & Informatics
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• v.14 no.4
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• pp.196-204
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• 2016

Many researchers have found that one of the most important characteristics of the structure of linkage disequilibrium is that the human genome can be divided into non-overlapping block partitions in which only a small number of haplotypes are observed. The location and distribution of haplotype blocks can be seen as a population property influenced by population genetic events such as selection, mutation, recombination and population structure. In this study, we investigate the effects of the density of markers relative to the full set of all polymorphisms in the region on the results of haplotype partitioning for five popular haplotype block partition methods: three methods in Haploview (confidence interval, four gamete test, and solid spine), MIG++ implemented in PLINK 1.9 and S-MIG++. We used several experimental datasets obtained by sampling subsets of single nucleotide polymorphism (SNP) markers of chromosome 22 region in the 1000 Genomes Project data and also the HapMap phase 3 data to compare the results of haplotype block partitions by five methods. With decreasing sampling ratio down to 20% of the original SNP markers, the total number of haplotype blocks decreases and the length of haplotype blocks increases for all algorithms. When we examined the marker-independence of the haplotype block locations constructed from the datasets of different density, the results using below 50% of the entire SNP markers were very different from the results using the entire SNP markers. We conclude that the haplotype block construction results should be used and interpreted carefully depending on the selection of markers and the purpose of the study.

• The Journal of the Acoustical Society of Korea
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• v.15 no.1
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• pp.61-70
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• 1996

According to topics or speaker's intentions in a dialogue, utterance spoken by speaker has a different sentence structure of word combinations. Based on these facts, we have proposed the statistical approach. IDT(intention decision table), which is modeling the correlations between sentence patterns and the intention. In a IDT, the sentence is splitted into 5 different factors, and the intention of a sentence is determined by the similarity between and intention and 5 factors that have represent a sentence. From the experimental results, the IDT has indicated that the prediction rate of an intention is improved 10~18% over the word-intention correlations and is enhanced 3~12% compared with the MIG(Markov intention graph) that models the intention with a transition graph for word categories in a sentence. Based on these facts, we have found that the IDT is effective method for the prediction of an intention.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.45 no.4
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• pp.60-67
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• 2008

This paper presents a new full-bridge soft switching PWM DC-DC converter circuit topology that adding two switcher, two lossless snubber quasi-resonance capacity, two diode to power source for general welding machine. This half bridge soft switching Is low voltage hight current output that first coil current is smaller than second coil current in high frequency transformer can be obtained with decreasing path loss in conventional DC bus line switcher. As it operate ZCS/ZVS in full range, high frequency, high efficiency and high output are implemented at low voltage and high DC current switching power supplies. All of this items are got from simulation and the result of experiment. If make up for the weak points of this proposed circuit, it will be used more easily for next generation TIG, MIG and MAG type of arc-welding machine.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.4
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• pp.1-7
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• 2021

In this study, MIG welding was performed on extruded 6005A-T6 material, which is used in the base panel of railway vehicles. The material was considered as the experimental base material, and argon shielding gas and ER5356 and ER4043 filler metals were used as the consumable welding materials. Welding coupons were prepared under various welding conditions by using an auto-welding system that various welding conditions applied 2.5Hz and 4.5Hz the pulse frequency of SynchroPuls function of welding machine and 1.0mm and 1.5mm of root face affect the weld penetration of welding joint. The welding current and voltage were also varied for this testing. On the basis of the results obtained, optimum welding conditions are proposed.