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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of The Korean Society of Manufacturing Technology Engineers
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The Korean Society of Manufacturing Technology Engineers
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Volume & Issues
Volume 21, Issue 6 - Dec 2012
Volume 21, Issue 5 - Oct 2012
Volume 21, Issue 4 - Aug 2012
Volume 21, Issue 3 - Jun 2012
Volume 21, Issue 2 - Apr 2012
Volume 21, Issue 1 - Feb 2012
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An Experimental Study of Ultra-precision Turning of High Transmittance Optical Glass(SF57HHT)
Kim, Min-Jae ; Lee, June-Key ; Hwang, Yeon ; Kim, Hye-Jeong ; Kim, Jeong-Ho ;
Journal of The Korean Society of Manufacturing Technology Engineers, volume 21, issue 2, 2012, Pages 191~195
DOI : 10.7735/ksmte.2012.21.2.191
Heavy flint optical glass(SF57HHT) is new material that has extremely high transmittance. Due to brittleness and high hardness, optical glass is one of the most difficult to materials for ultra-precision turning. According to the hypothesis of ductile machining, all materials, regardless of their hardness and brittleness, will undergo transition from brittle to ductile machining region below critical undefromed chip thickness. In this study, cutting test was carried out to evaluate cutting performance of heavy flint glass using ultra-precision machine with single crystal diamond bite. The machined workpiece surface topography, tool wear and surface roughness were examined using AFM and SEM. The experimental results indicate that the machining mode become the brittle mode to ductile mode, when the maximum undeformed chip thinkness is large than critical value. Tool wear mainly occurs on the flank face and its wear mechanism is dominated by abrasion. This study demonstrates the feasibility of SF57HHT by diamond turning.
A Study on Flow Characteristics in Muffler for 125cc Grade Motorcycle
Yi, Chung-Seob ; Jeong, In-Guk ; Yun, Ji-Hun ; Suh, Jeong-Se ;
Journal of The Korean Society of Manufacturing Technology Engineers, volume 21, issue 2, 2012, Pages 196~201
DOI : 10.7735/ksmte.2012.21.2.196
This study represents numerical study on the thermal and fluid flow characteristics of exhaust gas in a motorcycle muffler. The engine generates 125cc of displacement. Numerical analysis with computational fluid dynamics(CFD) was carried out to investigate the exhaust gas that flow into a motorcycle muffler. The STAR-CD S/W used to analyze three dimensional steady state and transient in a muffler. The Navier-Stokes Equation is solved with SAMPLE and PISO method in cartesian coordinates system. As the numerical result, it could be confirmed pulsating pressure generated from inlet of muffler become closer to the atmospheric pressure through baffle. Also the numerical result was almost identical to experimental result and, through the comparison, the reliability of numerical result was confirmed.
Finite Element Modeling of 2-stage Axially Deploying Beams Vibrating Under Gravity
Yun, Won-Sang ; Bae, Gyu-Hyun ; Beom, Hee-Rak ; Hong, Seong-Wook ;
Journal of The Korean Society of Manufacturing Technology Engineers, volume 21, issue 2, 2012, Pages 202~207
DOI : 10.7735/ksmte.2012.21.2.202
Multi-stage deploying beams are useful for transporting parts or products handling in production lines. However, such multi-stage beams are often exposed to unwanted vibration due to the presence of their flexibility and time-varying properties. This paper is concerned with dynamic modeling and analysis of 2-stage axially deploying beams under gravity by using the finite element method. A variable domain finite element method is employed to develop the dynamic model. A rigorous method to account for engagement of two-stage beams during the deploying procedure is introduced by breaking the entire domain into three variable domains. Several deploying strategies are tested to analyze the residual vibrations. Several examples are illustrated to investigate the self-induced damping and the effects of deploying strategy on the vibrations.
Performance Evaluation of Radial Error of a Rotary Table at Five-axis Machine Tool
Lee, Kwang-Il ; Yang, Seung-Han ;
Journal of The Korean Society of Manufacturing Technology Engineers, volume 21, issue 2, 2012, Pages 208~213
DOI : 10.7735/ksmte.2012.21.2.208
In this paper, the radial error of a rotary table at five-axis machine tool is evaluated by utilizing ISO 230-2 and estimation method using double ball-bar. The geometric error of a rotary table is defined as position dependent geometric errors or position independent geometric errors according to their physical character. Then estimation method of geometric errors using double ball-bar is simply summarized including measurement path, parametric modeling and least squares approach. To estimate representative radial error, offset error, set-up error which affect to the double ball-bar data, mean value of measured data including CCW/CW-direction are used at estimation process. Radial errors are separated from measured data and used for evaluation with ISO 230-2. Finally, suggested evaluation method is applied to a rotary table at five-axis machine tool and its result is analyzed to improve the accuracy of the rotary table.
A Study on the Ramp Design of Small Buses for the Mobility Handicapped
Lee, Jung-Hyun ; Kim, In-Cheol ;
Journal of The Korean Society of Manufacturing Technology Engineers, volume 21, issue 2, 2012, Pages 214~220
DOI : 10.7735/ksmte.2012.21.2.214
About 12 million people of the mobility handicapped were increased by the end of 2009 year. Universal design concept has been implemented in developed countries. Since 2004 low-floor buses are in Korea. In this study, there is no provision for mobility handicapped and small buses that can be comfortable riding car ramp design presented. The gate of a small buses lowered height of 200mm. Install the ramp in the center of the ramp by an air cylinder moves from side to side. The slope of the ramp was controlled by a hinge. Air cylinder thin type applicable in the narrow space of the slide cylinder was used.
Finite Element Analysis on the Strength Safety of a Hybrid Alarm Valve
Kim, Chung-Kyun ; Kim, Tae-Hwan ;
Journal of The Korean Society of Manufacturing Technology Engineers, volume 21, issue 2, 2012, Pages 221~224
DOI : 10.7735/ksmte.2012.21.2.221
This paper presents the strength safety of a hybrid alarm valve by a finite element analysis. The stress and strain of a conventional hybrid alarm valve are calculated for the given maximum test pressure of 2MPa. Especially, the FEM computed maximum stress of a conventional hybrid valve is only 18.6% of yield strength, 370MPa. This means that the conventional valve is designed with a thick thickness of a valve structure. But, new hybrid alarm valve model, which is developed by optimized design method in this study, shows more low level of 43% in maximum stress and strain compared with that of a conventional hybrid valve. These results may recommend the reduction of a weight and a dimension for an optimized hybrid alarm valve.
Board Level Drop Simulations and Modal Analysis in the Flip Chips with Solder Balls of Sn-1.0Ag-0.5Cu Considering Underfill
Kim, Seong-Keol ; Lim, Eun-Mo ;
Journal of The Korean Society of Manufacturing Technology Engineers, volume 21, issue 2, 2012, Pages 225~231
DOI : 10.7735/ksmte.2012.21.2.225
Drop simulations of the board level in the flip chips with solder joints have been highlighted for years, recently. Also, through the study on the life prediction of thermal fatigue in the flip chips considering underfill, its importance has been issued greatly. In this paper, dynamic analysis using the implicit method in the Finite Element Analysis (FEA) is carried out to assess the factors effecting on flip chips considering underfill. The design parameters are size and thickness of chip, and size, pitch and array of solder ball with composition of Sn1.0Ag0.5Cu. The board systems by JEDEC standard is modeled with various design parameter combinations, and through these simulations, maximum yield stress and strain at each chip are shown at the solder balls. Modal analysis is simulated to find out the relation between drop impact and vibration of the board system.
Efficient Method of Singular Value for Inverse Problem
Park, Sung-Oan ;
Journal of The Korean Society of Manufacturing Technology Engineers, volume 21, issue 2, 2012, Pages 232~240
DOI : 10.7735/ksmte.2012.21.2.232
This study proposed efficient method of singular value for inverse problem, linear approximation of contact position and loading in single and double meshing of transmission contact element, using 2-dimension model considered near the tooth by root stress. Determination of root stress is carried out for the gear tooth by finite element method and boundary element method. Boundary element discretization near contact point is carefully performed to keep high computational accuracy. The predicted results of boundary element method are good accordance with that of finite element method.
A Study on Energy Absorption Characteristics of Lightweight Structural Member according to Stacking Conditions
Choi, Ju-Ho ; Yang, In-Young ;
Journal of The Korean Society of Manufacturing Technology Engineers, volume 21, issue 2, 2012, Pages 241~245
DOI : 10.7735/ksmte.2012.21.2.241
In this study, one type of circular shaped composite tube was used, combined with reinforcing foam and without foam. Furthermore, CFRP (Carbon Fiber Reinforced Plastic) circular member manufactured from CFRP prepreg sheet for lightweight design. CFRP is an anisotropic material which is the most widely adapted lightweight structural member. The crashworthy behavior of circular composite material tubes subjected to static axial compression under same conditions is reported in this paper. The collapse mode during the failure process were observed and analyzed. The behavior of polymeric foams to the tubes crashworthiness were also investigated.
AFM based Surface Verifications of Pulse Electrochemical Polishing for Various Frequency Conditions
Kim, Young-Bin ; Kim, Jong-Tye ; Ahn, Dong-Gyu ; Park, Jong-Rak ; Jeong, Sang-Hwa ; Park, Jeong-Woo ;
Journal of The Korean Society of Manufacturing Technology Engineers, volume 21, issue 2, 2012, Pages 246~251
DOI : 10.7735/ksmte.2012.21.2.246
Pulse electrochemical polishing process has been used to improve mechanical properties such as surface roughness and corrosion resistance on conductive metallic materials. In addition, pulse electrochemical polishing process with various frequency may produce a lustrous, smoother, deburred and cleaned surface on workpiece. The aim of this paper is to study surface characteristics of pulse electrochemical polishing for various frequency conditions using AFM to verify localized surface variation in nanometer scale.
Nondestructive Evaluation in the Defects of FRP Composites By Using Terahertz Waves
Im, Kwang-Hee ; Kim, Ji-Hoon ; Hsu, David K. ;
Journal of The Korean Society of Manufacturing Technology Engineers, volume 21, issue 2, 2012, Pages 252~258
DOI : 10.7735/ksmte.2012.21.2.252
A study of terahertz waves was made for the nondestructive evaluation of FRP (Fiber reinforced plastics) composite materials. The terahertz systems were consisted of time domain spectroscopy (TDS) and continuous wave (CW). The composite materials investigated include both non-conducting polymeric composites and conducting carbon fiber composites. Terahertz signals in the TDS mode resembles that of ultrasound; however, unlike ultrasound, a terahertz pulse was not able to detect a material with conductivity. The CFRP (Carbon fiber reinforced plastics) laminates were utilized for confirming the experimentation in the terahertz NDE. In carbon composites the penetration of terahertz waves is quite limited and the detection of flaws is strongly affected by the angle between the electric field direction of the terahertz waves and the intervening fiber directions. A refractive index (n) was defined as one of mechanical properties; so a method was obtained in order solve the "n" in the material with non-conductivity. The usefulness and limitations of terahertz radiation are investigated for the NDE of FRP composites.
Simulation Analysis on the Air Flow Inside Computer Main Frame According to the Location of Fan
Cho, Jae-Ung ; Han, Moon-Sik ;
Journal of The Korean Society of Manufacturing Technology Engineers, volume 21, issue 2, 2012, Pages 259~266
DOI : 10.7735/ksmte.2012.21.2.259
In this study, the temperature distributions are analyzed on the air flow according to the position of fan inside computer main frame by CFD simulation. In case that ventilation hole is existed at the side of computer frame, the air with lower temperature can be circulated near CPU radiant thermal panel. In case of installation with fan at the side panel, the temperature of air flow becomes lowest. The efficiency of thermal emission at personal computer and its durability can be improved by releasing a lot of heat at air flow effectively inside computer frame according to this simulation result.
Evaluation of Material Properties in Austenite Stainless Steel Sheet with Scanning Acoustic Microscopy
Park, Tae-Sung ; Kasuga, Yukio ; Park, Ik-Keun ; Kim, Kyoung-Suk ; Miyasaka, Chiaki ;
Journal of The Korean Society of Manufacturing Technology Engineers, volume 21, issue 2, 2012, Pages 267~275
DOI : 10.7735/ksmte.2012.21.2.267
Austenite stainless steel 304 has properties of high resistance to corrosion and temperature changes. Therefore, this material is widely used in various of industries. However, when the material is subjected to heating and cooling cycles the forming accuracy, for example, the right angle associated with a sharp bend such as corner is lost. This phenomenon is caused by the reversion of the deformation-induced martensite into austenite when the temperature in increased. This result in misfit of a structure or an assembly, and an increase in residual stress. Hence, it is important to understand this process. In this study, to evaluate the mechanical behavior of the deformation-induced martensite and reversed austenite, a scanning acoustic spectroscope including the capability of obtaining both phase and amplitude of the ultrasonic wave (i.e., the complex V(z) curve method) was used. Then, the velocities of the SAW propagating within the specimens made in different conditions were measured. The experimental differences of the SAW velocities obtained in this experiment were ranging from 2,750 m/s to 2,850 m/s, and the theoretical difference was 3.6% under the assumption that the SAW velocity was 2,800 m/s. The error became smaller as the martensite content was increased. Therefore, the SAW velocity may be a probe to estimate the marternsite content.
Crack Growth Behavior by Fatigue Load under Mixed Mode(I+II)
Gong, B.C. ; Choi, S.D. ;
Journal of The Korean Society of Manufacturing Technology Engineers, volume 21, issue 2, 2012, Pages 276~282
DOI : 10.7735/ksmte.2012.21.2.276
This study looked for Mode status of each for fatigue crack growth behavior about the repeat load of mode I and the static load of mode II. The experiment was performed in the state of the repetition frequency of the sine wave 10Hz, the stress ratio 0.1, maximum load 300kg.f, a static load 0, 100, 200, 300kg.f, As the experimental results, in mode of static load, while the load value increases, the crack growth rate is slower as the energy of a crack mixing grows. Mode I and the power mode II get an influence each other in the direction of crack propagation path, but as they eventually get closer to the breaking point of the crack growth, it is dominated by the mode I.
Pitting Life of CRP System
Kim, Chang-Hyun ; Nam, Hyoung-Chul ; Kwon, Soon-Man ;
Journal of The Korean Society of Manufacturing Technology Engineers, volume 21, issue 2, 2012, Pages 283~289
DOI : 10.7735/ksmte.2012.21.2.283
Cam rack pinion (CRP) system which consists of cam rack and roller pinion transforms the rotation motion into linear one. The roller pinion has the plurality of rollers and meshes with its conjugated cam rack. The exact tooth profile of the cam rack and the non-undercut condition to satisfy the required performance have been proposed by introducing the profile shift coefficient. The load stress factors are investigated by varying the shape design parameters to predict the gear surface fatigue limit which is strongly related to the gear noise and vibration at the contact patch. The results show that the pitting life can be extended significantly by increasing the profile shift coefficient.
A Study on Fatigue Characteristics for Design Automation of TS-Type Spot Welded Lap Joint
Yeb, Baek-Seung ; Ho, Bae-Dong ;
Journal of The Korean Society of Manufacturing Technology Engineers, volume 21, issue 2, 2012, Pages 290~296
DOI : 10.7735/ksmte.2012.21.2.290
Cold-rolled carbon steel sheets are commonly used in railroad car or commercial vehicles such as the automobile. These are mainly fabricated by spot welding which is a kind of electric resistance welding. But fatigue strength of spot welding joint is lower than that of base metal due to high stress concentration at nugget edge of the spot welded part. And fatigue strength of them is especially influenced by not only geometrical and mechanical factors but also welding conditions of the spot welded joint. So for fatigue design of gas welded joints such as TS-type joints, it is necessary to obtain design information on stress distribution at the weldment as well as fatigue strength of spot welded joints. And also, the influence of the geometrical parameters of spot welded joints on stress distribution and fatigue strength must be evaluated. And analysis approach for fatigue test using design of experiment are evaluated optimum factor in TS-type welded joint and geometrical parameters of materials. Using these results, that factors applied to fundamental information for automation of fatigue design.
A Study on the RFID Tag Package Epoxy Molding through Leak Detection
Ban, Chang-Woo ; Hong, Seok-Kee ; Jang, Dong-Young ;
Journal of The Korean Society of Manufacturing Technology Engineers, volume 21, issue 2, 2012, Pages 297~304
DOI : 10.7735/ksmte.2012.21.2.297
Recently RFID (Radio Frequency Identification) technology advances in wireless communication technologies are bringing new challenges. But RFID tag packaging technology has been lagging compared to the demand, so this technology is being required to improve reliability. In this paper, reliability comparison among 11 types of most commonly used epoxy molding in electrical/electronic components packaging has been made through analysis of confidentiality using a humidity sensor. Consequently, the variation of moisture penetration time causes has been verified by the changes in molding thickness for 3 types of epoxy, and from the result, the best experimental results were observed in terms of confidentiality. Moreover we have been confirmed the relationship between confidentiality, the molding thickness, and thermal property of epoxy through thermal analysis.
Development of Normal-Opposite Rotational Durability Test Equipment for Large Sized Planetary Gear Box
Lee, Yong-Bum ; Kim, Kwang-Min ;
Journal of The Korean Society of Manufacturing Technology Engineers, volume 21, issue 2, 2012, Pages 305~310
DOI : 10.7735/ksmte.2012.21.2.305
Planetary gear box is a power transmitter having very high gear ratio in compact volume. The planetary step-down gear box converts high speed and low torque into low speed and high torque, which is widely used in constructional and industrial machinery field. And, the planetary step-up gear box does vice versa working, which is used as main gear box of large sized wind mill system. The large sized planetary gear box must be performed the normal-opposite rotation test as a its durability test for achieving the reliability. The large sized planetary gear box is composed by triple gear trains of sun gear, carrier, and ring gear. If input power is supplied into one of them and the other is fixed, and then another becomes the output part. In this paper, we designed a new test equipment which can do rapid normal and opposite rotational change with only small displacement by supplying test power using the above rotation (driving) characteristics and hydraulic cylinder and link, and also compared and analyzed with existing method through various experiments.
Internal Flow Analysis and Structural Design in Plastic Automatic Control Valve for the Semiconductor Chemical Liquid
Lee, Gyu-Hoon ; Lee, Eung-Suk ; Lee, Min-Ki ; Kim, Jin-Su ; Bae, Il-Jin ;
Journal of The Korean Society of Manufacturing Technology Engineers, volume 21, issue 2, 2012, Pages 311~315
DOI : 10.7735/ksmte.2012.21.2.311
Diaphragm type noncontact automatic control valve is a valve for controling acidic PR(Photo Resist) liquid used in the semiconductor process. PR is photosensitive liquid that changes phases depending on light transmittance. PR is very toxic and expensive; the purpose of this paper is to address methods that prevent loss due to leaks. The design of noncontact precise automatic control valve is expected to play an important role in controlling fluid flow, therefore influencing energy conservation and environmental improvement. In this paper, diaphragm type automatic control valve`s part design, assembly and simulation are introduced. Also, through the analysis of fluid flow the valve`s internal velocity, pressure, and turbulent intensity are interpreted. This paper proposes to contribute to the improvement of the valve`s performance.
Planet Bearing Design of Slewing Planetary Gearbox
Park, Young-Jun ; Lee, Geun-Ho ; Song, Jin-Seop ; Nam, Yong-Yun ; Park, Sung-Ha ;
Journal of The Korean Society of Manufacturing Technology Engineers, volume 21, issue 2, 2012, Pages 316~323
DOI : 10.7735/ksmte.2012.21.2.316
In order to meet the service life of planetary gearbox, a planet bearing, well known as the component with the highest failure rate, is designed. To predict the bearing fatigue life, ISO standard(ISO/TS 16281) is used, and the design parameters of the bearing are optimized using a parametric method. The whole planetary gearbox model is developed using a commercial software to calculate loads acting on planet bearings accurately. The results state that the designed bearings are satisfied with the life of 15,000hours, and the bearings that consist of 22rollers of 58mm have 1.6times longer life and better load sharing relatively than 22rollers of 28.5mm. Also, the increase in preload of taper roller bearings on the output pinion shaft prolongs the life of planet bearings regardless of roller`s length.
A Robust Control System Design for Compensating Hysteresis of a Piezoelectric Actuator-based Actuation Unit
Kim, Hwa-Soo ; Kim, Jong-Won ;
Journal of The Korean Society of Manufacturing Technology Engineers, volume 21, issue 2, 2012, Pages 324~330
DOI : 10.7735/ksmte.2012.21.2.324
In this paper, we presents a robust control system design for compensating hysteresis of a piezoelectric actuator-based actuation unit. First, the dynamics between the input voltage and the output displacement of the actuation unit are unravelled via a non-parametric system identification method. From the dynamic characteristics of those experimental transfer functions, a parametric model is then derived, whose dynamics match those of the non-parametric ones under various conditions on input voltages. A robust controller is constructed on the basis of this parametric model in order not only to effectively compensate the hysteresis of the actuation unit but also to guarantee the robust stability. Extensive experiments show that the proposed robust control system successfully mitigate the effect of the hysteresis and improve the tracking capability of the actuation unit.
A Study on the Cold Forging Development of Guide Valve for the Fuel Pressure Regulator
Song, Seung-Eun ; Kwon, Hyuk-Hong ;
Journal of The Korean Society of Manufacturing Technology Engineers, volume 21, issue 2, 2012, Pages 331~336
DOI : 10.7735/ksmte.2012.21.2.331
This study was aimed at the design of the dies for the guide valve for the fuel pressure regulator using the computer simulation to shorten the period of production, on the basis of the process planning which was designed by the field experts. In the computer simulation, `Deform-3d` and `Eesy-DieOpt` have been used, which are the commercial process analysis and die design program. Through the process analysis, we could know the propriety of the forming process, the inner pressure of the die and the suitable fitting pressure between the insert and the sleeve which was not showing any positive tangential stresses in the insert. Through the simulation of die design, we could know the number of the stress ring, the diameter ratios, the stresses of the die, the shrink fitting tolerance and temperature in the condition of the already determined maximum outer die diameter of the multi-stage former. The validity of the die design using the computer simulation was analyzed by the experiments and the results were satisfactory. As the results of this study, the new and easy die design system for multi-forging has been developed.
Vibrational Characteristics of the Gas Pipelines Conveying Flow
Kim, Kyung-Tae ; Lee, Sung-Soo ; Lee, Seong-Woo ;
Journal of The Korean Society of Manufacturing Technology Engineers, volume 21, issue 2, 2012, Pages 337~343
DOI : 10.7735/ksmte.2012.21.2.337
This work investigates the vibrational characteristics of the underground gas pipelines. Experiments were conducted to analyze the effects of various parameters on the vibrational characteristics from the emergency detection point of view. Influences of the various types of impact exerted on the pipe, height of free fall and measuring locations were analyzed. Especially, the difference between the vibrational signal generated by the direct impact on the pipe and the ambient noise was successfully identified. To validate the experimental observation, computer simulation was also performed with constant properties(elasticity, fluid velocity and internal pressure) which are directly conjectured from the accompanying experiment with a real pipe system.
Structural Optimization of the Knuckle Crane Installed in Truck
Lim, Hun-Bong ; Shin, Moon-Kyun ; Yang, Hyun-Ik ;
Journal of The Korean Society of Manufacturing Technology Engineers, volume 21, issue 2, 2012, Pages 344~348
DOI : 10.7735/ksmte.2012.21.2.344
The knuckle crane design in Korea has been performed by assuming a cantilever beam type structure and numerically analyzing design data and finally improving the stiffness by replacing material. In our study, a complete finite element model of the knuckle crane is constructed and finite element analysis is conducted using Optistruct. Structural optimization to reduce the weight of the knuckle crane is processed by applying maximum loading condition at the largest radius of motion, which is the worst case of loading condition. As the results, existing over stiff design in a knuckle crane is corrected to meet a desired design limit and overall weight is reduced, which eventually leads to a reduction of
Study of Welding Toughness Characteristics on the Root-pass Welding Process of High Tensile Steel at Tower Production for Offshore Wind Power Generation
Jung, Sung-Myoung ; Kim, Ill-Soo ; Kim, Ji-Sun ; Na, Hyun-Ho ; Lee, Ji-Hye ;
Journal of The Korean Society of Manufacturing Technology Engineers, volume 21, issue 2, 2012, Pages 349~353
DOI : 10.7735/ksmte.2012.21.2.349
As the world wind energy market grows rapidly, the productions of wind power generation equipment have recently increased, but manufacturers are not able meet this requirement. Particularly offshore wind energy industry is one of the most popular renewable energy sectors. To generalize welding processes, the welding automation is considered for steel structure manufacturing in offshore wind energy to get high quality and productivity. Welding technology in construction of the wind towers is depended on progress productivity. In addition, the life of wind tower structures should be considered by taking account of the natural weathering and the load it endures. The root passes are typically deposited using Gas Tungsten Arc Welding(GTAW) with a specialized backing gas shield. Not only the validation consists of welders experienced in determining the welding productivity of the baseline welding procedure, but also the standard testing required by the ASME section IX and API1104 codes, toughness testing was performed on the completed field welds. This paper presents the welding characteristics of the root-pass welding of high tensile steel in manufacturing of offshore wind tower. Based on the result from welding experiments, optimal welding conditions were selected after analyzing correlation between welding parameters(peak current, background current and wire feed rate) and back-bead geometry such as back-bead width(mm) and back-bead height performing root-pass welding experiment under various conditions. Furthermore, a response surface approach has been applied to provide an algorithm to predict an optimal welding quality.