• Journal of Welding and Joining
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• v.30 no.3
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• pp.66-70
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• 2012

Welding is an essential process in the automotive industry. Most welding processes that are used for auto body is spot welding. And $CO_2$ arc welding is used in a small part. In production field, $CO_2$ arc welding process is decreased and spot welding process is increased due to welding quality is poor and defects are occurred in $CO_2$ arc welding process frequently. But $CO_2$ arc welding process should be used at robot interference parts and closed parts where spot welding couldn't. $CO_2$ welding is divided into lap welding and plug arc spot welding. In case of plug arc spot welding, burn through and under fill were caused in various welding environment such as different thickness combinations of base metal, teaching point, over the two steps welding and inconsistent voltage/current. It makes some problem like poor quality of welding area and decrease the productivity. In this study, we will evaluate the effect of teaching point through the weld pool behavior and bead geometry in the arc spot welding at the plut hole. Welding position is horizontal position. And galvanized steel sheet of 2.0mm thickness that has plug hole of 6mm diameter was used. Teaching point was changed by center, top, bottom, left and right of the plug hole. At each condition, the phenomenon of weld pool behavior was confirmed using a high-speed camera. As the result, we find the center of plug hole is the most optimal teaching point. In the other teaching point, under fill was occurred at the plug hole. This phenomenon is caused by gravity and surface tension. For performance of arc spot welding at the plug hole, the teaching condition should be controlled at a center of plug hole.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.8
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• pp.718-723
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• 2007

The new concept spark plug was developed to study its influence on the combustion characteristics of SI engine. It has pre-ignition chamber in the lower end of spark plug and flame hole, in which fresh mixture gas can be introduced without any fuel supply system. This spark plug was tested with a commercial SI engine. Fuel consumption rate, emission gas and MBT timing were measured in the engine dynamometer for various flame hole numbers, hole positions, hole sizes of the pre-ignition chamber of the spark plug. And average flame propagation speed was measured by using the head gasket ionization probe in single cylinder engine. The new concept spark plug induces fast bum in combustion compared with the conventional spark plug, and MBT(Minimum advance for Best Torque) timing was retarded about $3{\sim}5^{\circ}$ crank angle. The flame hole number, hole direction and volume of pre-ignition chamber were found to influence the combustion characteristics.

• Journal of Welding and Joining
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• v.17 no.2
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• pp.29-35
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• 1999

This study was intended to use for the fatigue test in real structures and offer basic data for optimum welding structure design. To this purpose, we obserded the effect of the size and distance of plug welding hole on the static strength and fatigue life of welding structure under the shear/bending load for the improvement of fatigue life of plug welding joint between S/MBR and C/MBR in the lower structure of large bus. The result below is shown through this study. 1) Static and fatigue strength are strongly influenced by the direction of plug weld hole distributed. 2) Distances and diameters of the distributed holes are little dependent on the static strengths 3) In case of the directions of the distributed plug weld holes are vertical to the loading pin, fatigue life is dependent on distance of the distributed hole. 4) In case of the directions of the distributed plug weld holes are parallel to the loading pin, fatigue life is dependent on distance of the hole diameter.

• Journal of the Korean Society of Visualization
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• v.14 no.3
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• pp.51-58
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• 2016

New concept spark plug was developed to study its influence on the combustion characteristics of SI engine. It has pre-ignition chamber at the lower end of spark plug and flame hole, in which fresh mixture gas can be put in through the flame hole without any fuel supply system. This spark plug was tested in a single cylinder engine dynamometer for different air fuel ratio to measure the fuel consumption rate, emission gases, and MBT timing. And constant volume combustion chamber was made to understand flame characteristics of spark plug. New spark plug induced fast burn compared to the conventional spark plug and its effects were increased in lean air fuel ratio. Pre-ignition chamber spark plug with 5 holes which had adjusted size was more stable and effective in combustion performance than pre-ignition chamber spark plug with 1 hole. And its effects showed larger differences in lean air fuel ratio than stoichiometric condition. Flame kernel and flame growth process of conventional spark plug and pre-ignition chamber spark plug studied by flame visualization of schlieren method.

• Journal of Ocean Engineering and Technology
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• v.8 no.1
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• pp.96-104
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• 1994

The use of advanced composite materials has grown in recent years in aerospace and other structures. Out of various kinds of repairing methods the one selecteh for this study is an idealized case which simulates a situation where a damaged laminate has been repaired by drilling a hole and therefter plugging the hole with reinforcement. Two typesof reinforcement are investigated ;adhesively bonged plug reinforcement or snug-fit unbonded plug in the hole. For each case of reinforcement, four different sizes of hole diameter and three types of reinforcing material(steel, aluminum, plexiglass) are employed for investigation. The experiment are mainloy forced on the evaluation of ultimate strength of laminate with reinforced hole in comparison to its counterpart with the open hole.

• Journal of the Microelectronics and Packaging Society
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• v.22 no.4
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• pp.71-76
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• 2015

Recently, light emitting diodes (LEDs) have been studied to improve their efficiencies for the uses in various fields. Particularly in the aspect of chip structure, via hole type vertical LED chip is developed for improvement of light output power, and heat dissipations. However, current vertical type LEDs have still drawback, which is current concentration around the n-contact holes. In this research, to solve this phenomenon, we introduced isolation layer under n-contact electrodes. With this sub-electrode, even though the active area was decreased by about 2.7% compared with conventional via-hole type vertical LED, we could decrease the forward voltage by 0.2 V and wall-plug efficiency was improved approximately 4.2%. This is owing to uniform current flow through the area of n-contact.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.5
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• pp.593-602
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• 1999

This paper presents combustion characteristics of LPG-air mixture ignited by the plasma jet in a cylindrical vessel with constant volume, in which our focus is placed on the multi-hole plug configuration. Four types of the plug configuration depending on the number of orifice and the arranged angle are considered, along with two cases of conventional spark ignition for comparison. Not only the flame propagation is photographed at intervals, but the pressure in the combustion chamber is also recorded through the entire combustion process. The results show that the plasma jet ignition enhances the overall combustion rate remarkably in comparison to the spark ignition by generating irregular flame front and penetrating through the unburned mixture. The combustion enhancement rate agrees favorably with the available data, which supports the validity of our experiment. Synthetically estimating, the two-hole sixty-degree plug appears to be the most desirable, in that the maximum pressure as well as the combustion duration is less affected by the sub-energy level than the others. It is also deduced that there may exist an optimal plug configuration capable of rapid combustion for a specific combustion chamber.

• Journal of Welding and Joining
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• v.16 no.1
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• pp.106-113
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• 1998

In this study, the plug weldability of STS 304 was investigated. The parameters which influence plug weldability were pushing pressure of the plates, position of welding wire and composition of shielding gases. Among these factors, the composition of shielding gases and hole diameter of the upper plate were found to be the major factors influencing weld quality. To evaluate weldability, tensile shear strength of the plug welded specimen was measured and compared with tensile strength of butt welded specimen. Hardness was measured for both plug weld and butt weld. The microstructure of the weld metal and HAZ were also characterized.

• Journal of Biosystems Engineering
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• v.23 no.3
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• pp.259-270
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• 1998

An automatic seedling transplanter, employed an innovative plug-seedling feeder was developed by improving the problems of conversational feeding and transplanting mechanisms. With conventional methods, missing and damage rates of seedling were high for long seedlings over 20cm and also breaking seed-bed was frequently observed. Thus, a pushout-bucket slide-hopper type trandsplanter was devised and tested. Test results of picking and transferring accuracies of the developed transplanter are as follows : A prototype transplanter performed with 1.5% of missing rate. The deviations of horizontal feed ranged from -0.3mm to 2.8mm and averaged 0.673mm for the 128-hoe test tray : and ranged from -lmm to ＋3mm and averaged 0.785mm for the 200-hole test tray. The deviations could decrease with precise manufacturing and lightening the mechanism. The maximum and deviations of vertical feed were -2.3mm and + 1mm, respectively, for the 128-hole test tray ; and were ＋3mm and ＋2.5mm, respectively, for the 200-hole test tray. The missing rate, seeding bruise rate and seed-bed damage rate were esitmate to be 1.3％, 0.4% and 3.5％, respectively, with the developed automatic transplanter.

• Journal of Biosystems Engineering
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• v.35 no.5
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• pp.330-335
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• 2010

Soybean (Glycine max Merr.) and corn (Zea mays L.) transplanting has increased because soybean and corn crops cultivated by the direct seeding method were often damaged by wild birds. The purpose of this study is to develop a seeder to sow soybean (Glycine max Merr.) and corn (Zea mays L.) in a plug tray. In order to find out design factors for a metering device of the seeder, metering characteristics on metering hole size and roller speed were experimentally investigated. Soybean (cv. 'Daewon') and corn (cv. 'Mibaekchal') were used as a materials for testing the seeder in this experiment. The metering hole size of roller suitable for Daewonkong and Mibaekchal was determined. Daewonkong was suitable for hole diameter of 10 mm and hole depth of 5.5 mm, and Mibaekcal was suitable for hole diameter of 9 mm and hole depth of 5.5 mm. At a brush length of 4 mm, one grain seeding rates of Daewonkong and Mibaekchal was 99% and 93% respectively. By inducing Mibaekchal to the hole by swing, one grain seeding rate of that increased from 91.9% to 97.7%. When roller speed is 4 m per minut, seeding efficiency of prototype was 110 sheets per hour.