• Transactions of the Korean Society of Mechanical Engineers
• /
• v.18 no.1
• /
• pp.212-222
• /
• 1994

In the annular Modified Chemical Vapor Deposition process using two concentric tubes, the inner tube is heated to maintain high temperature gradients to have high thermophoretic force which can increase particle deposition efficiency. However, higher axial velocity in a narrow gap between inner and outer tubes can result in a longer tapered entry length. In the present paper, a new concept using an annular jet from the inner tube is presented and shown to significantly reduce the tapered entry length with maintaining high efficiency. Effects of a jet injection on heat transfer, fluid flow and particle deposition have been studied. Of particular interests are the effects of jet velocity, jet location and temperature on the deposition efficiency and tapered length . Torch heating effects from both the previous and present passes are included and the effect of surface radiation between inner and outer tubes is also considered.

• Transactions on Electrical and Electronic Materials
• /
• v.2 no.4
• /
• pp.7-10
• /
• 2001

A new possibility of our atmospheric cold plasma torch has been examined on the surface treatment of an air-exposed vulcanized rubber compound. The plasma treatment effect was evaluated by the bondability with another rubber compound using a polyurethane adhesive. The adhesion property was improved by the treatment with plasma containing oxygen radicals. The oxygen radical generation from the plasma was verified and its efficiency was found to be dependent on the cathode material.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.5 no.3
• /
• pp.238-245
• /
• 2000

본 논문은 펄스 인버터용 TIG(Tungsten Inert Gas) 아크 용접기를 구현하는 용접전원장치의 성능에 관하여 알아본다. 용접전류는 펄스형태로 제어되고 또한 안정된 아크와 좋은 용접성능을 얻을 수 있다. DC 고전압 아크 스타트 시스템을 채용한 TIG 아크용접기에 대해 토치와 용접전원 사이의 연장 케이블이 50m 나 되어도 아크 스타트이 실패 없이 용접을 행할 수 있음을 알 수 있었다. 따라서, 이 DC 고전압 아크 스타트방식을 이용한다면 용접 전원장치와 용접장이 멀리 떨어져 있는 조선소와 같은 장소에서 요용하리라 생각된다. 이를 확인하기 위하여 시뮬레이션 및 실험을 행하였다.

• Proceedings of the KIEE Conference
• /
• 2007.11a
• /
• pp.188-189
• /
• 2007

Axial magnetic field was applied into the hollow anode of plasma torch for the purpose of extension of electrode lifetime. The average arc voltage increased because the arc column became longer, the arc voltage ripple frequency became low. The steady state of arc voltage was removed by applied magnetic filed. The lifetime of electrode was over 1000 hours which is 100 times longer than operation without magnetic field.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.4 no.4
• /
• pp.885-893
• /
• 2000

The use of neural-fuzzy system to model mesh seam welding is described in this paper. Conventional, automated process generally involves sophisticated sensing and control techniques applied to various processing parameters. Welding parameters affecting quality include the arc voltage, the welding current, torch travel speed and the pressure and so on. The relationship between the welding parameters and weld quality is not a direct one, and in addition, the effect of the weld parameter variables are not independent of the each other. The effectiveness of the proposed neuro-fuzzy algorithms is demonstrated by computer simulations.

• Journal of Welding and Joining
• /
• v.27 no.6
• /
• pp.55-61
• /
• 2009

This study aims for determination of cutting work envelope of an articular robot for H-beam cutting. The robot has its own work envelope. The cutting of piece with groove requires the specific position of the torch which contracts the work envelope. This study suggested the new method to determine the cutting work envelope for this case. The method simplified the problem by use of the combination of inverse kinematics and forward kinematics. The method was used for cutting the H-beam with groove. The cutting work envelope was determined easily. The result was verified by 3D simulation system which implements the articular robot with 6 axes and the H-beam in the virtual shop.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.19 no.3
• /
• pp.201-206
• /
• 1990

The optimal cultural conditions for production of the bluish purple prgment by the cultivation of Streptomyces californicus KS-89 were determined with various substrates. The carbon and nitrogen sources on the production of pigment indicated that soluble strarch and glycerol as carbon sources and sodium glutamate sodium nitrate as nitrogen sources given a mzimum yield of the pigment at 3$0^{\circ}C$ for 7 days. The addition of ferrous sulfate was essential. The highest production of pigment was observed with cultivation in a medium containing 2.0% soluble starch 1% glycerol 0.5% sodium glutamate 0.05% sodim nitrate 0.001% L-proline 0.025% K2HPO4 0.005% MgSO4 .7H2O, 0.04% FeSO4.7H2O, 0.001% thiamine.HCl and pH7.0.

• Plant Journal
• /
• v.4 no.4
• /
• pp.62-70
• /
• 2008

PGV(Plasma Gasification & Vitrification) system has been developed based on a pyrolysis melting gasification technology that provides the possibilities of acquiring renewable energy. As volume of wastes increases with the rapid industrialization and population growth, eco friendly disposal is drawing more social attention. Pyrolysis plasma technology is regarded as the best environmentally friendly process for the waste disposal among numerous waste disposal processes. Introduced in this paper is the behavior of the plasma torch and a computational fluid simulation dynamics is discussed for designing the melting furnace. Some PGV applications have also been discussed.

• Nuclear Engineering and Technology
• /
• v.54 no.3
• /
• pp.1145-1151
• /
• 2022

A hybrid cutting using both plasma and end mill was developed for safe and efficient dismantling of nuclear facilities. In this cutting method, a moving arc plasma heats up the workpiece before milling. Thermally softened part of the workpiece is then removed quickly and deeply with an end mill. For the cutting experiments, a three-axis numerical control (NC) milling machine was combined with a commercialized arc plasma torch and used to cut 25 mm thick stainless steel plates. Experimental results revealed that pre-heating by arc plasmas can improve the cutting volume per unit time higher than 40% by reducing the cutting load and increasing the cuttable depth when using an end mill without cutting fluids. These advantages of a hybrid cutting process are expected to contribute to quick and safe segmentations of metal structures with radioactively contaminated inner surfaces.

• International Journal of Korean Welding Society
• /
• v.1 no.1
• /
• pp.71-77
• /
• 2001

The characteristics of the fume generation in a flux cored arc welding were investigated using the fume collection chamber developed. The Korean Standard concerning the method for the evaluation of the fume generation rate(FGR) was updated by the evaluation method obtained through this study. It was found that the effect of humidity in the test environment should be considered and the automatic welding method had to be employed for the purpose of the exact evaluation of the fume generation rate. The results showed that the fume generation rate was influenced by the welding parameters. The important factors were the welding current arc voltage, travel speed, and contact tip to work distance(CTWD) that affected the heat input as well as the torch angle and the shielding gas flow rate that influenced the shielding effect. The fume generation rate increased as the heat input increased and the shielding effect decreased. It was also observed that the effect of the welding current is much grater than the other welding parameters.