• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2000.04a
• /
• pp.417-422
• /
• 2000

In the process of die manufacturing, according to increasing demand of die and molds, the efficient machining of dies and molds has been increased. However, while the cutting process has been automated by the progress of CNC(computer numerical control) and CAD/CAM, the polishing process still depends on the experienced knowledge of an expert. Also, even when workers are skilled in polishing dies. it takes much time to obtain the required roughness and smoothness on the surface of a die. Moreover, many workers gradually avoid doing polishing work because of the poor working conditions caused by dust and noise. Therefore, to improve productivity and to solve the potential shortage of skilled workers, a user-friendly automatic polishing system was developed in this research. The developed polishing system with five degrees of freedom is able to keep the polishing tool normal to the die surface during operation and is able to maintain a pressure constantly by the developed pneumatic system. Also, to evaluate polishing performance of the developend system and find the polishing conditions, the various polishing experiments were carried out.

• Journal of the Korean institute of surface engineering
• /
• v.36 no.3
• /
• pp.272-283
• /
• 2003

Mild steel and zinc specimens were tested in five atmospheric testing sites of Vietnam in order to collect the corrosion databank as well as to study the corrosion mechanism in tropical conditions, in period of 1997-2000. The results obtained showed that the corrosion rate of steel is in the range of $10-50\;{\mu}m/year$ and of zinc is of $1-5\;{\mu}m/year$. They are interpretable in the comparison with the data obtained in different countries in the South East Asian as well as previous reports of Vietnamese nation project In atmospheric corrosion. The main factors affecting the corrosion in Vietnam tropical conditions are TOW (time of wetness) and salinity. The relationship between sulfur dioxide and corrosion of metals, particularly, zinc was not found clearly. An explanation was suggested about the complex effect of different pieces present in tropical atmosphere and about the alternative of the dominant factors such as humidity, salinity or temperature.

• Journal of the Korean institute of surface engineering
• /
• v.22 no.1
• /
• pp.26-42
• /
• 1989

It has between investigated that the optimum spaying conditions, such as, spraying distance, fusing temperature and fusing time, ect, in a Ni-cr base self fluxing alloy sprayed on the mild steel substrate by oxygen-acetylenc flame spraying. Sprayed specimens on various conditions were fuused in a vacuum furnace and the results were as follows. The optimum spraying condition for excellent coating layer are obtained under spraying distances, fusing temperature and fusing and time ; 180~240mm,1050~110$0^{\circ}C$and 15~30min, respectively. The adhesive strength and surface hurface hardness of the as sprayed specimens were very low by mechanical bonding becaus of the diffusion layer during process. The carbides and borides and formed in the sprayed coating layer and densification of the layer was resulted from the elimination of pores and oxides. The hardness of sprayed coating layer, particularly in the high temperature, was superior to ordinary tool steels.

• Journal of the Korean institute of surface engineering
• /
• v.44 no.4
• /
• pp.137-143
• /
• 2011

The internal stress and magnetic properties (coercivity and squareness) of Ni-Fe nano thin film synthesized by electrodeposition method were studied as a function of acidic chloride bath conditions (composition and temperature) and current density. Fe deposition patterns were different depending on the temperature of the solution, the stress of film decreased with increasing the solution temperature, and the depending on the amount of Fe deposition showed a parabolic shape. The grain size of film was inversely proportional to stress of thin film. The internal stress of thin film and magnetic properties were deeply relevant, and the stress of thin film had a relationship with bath conditions and grain size of the thin film surface.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 1997.04a
• /
• pp.185-191
• /
• 1997

The study presents the linear dynamic analysis of bridges under vehicular movement to examine the performance characteristics due to the various structural and loading conditions. The road surface roughness and bridge-vehicle interactions are considered. The road surface profiles for the approaching roadway and bridge decks are generated from power spectral density functions for different road roughness conditions. A new filtering method using the wheel trace is proposed to obtain the more rational bridge-vehicle interactions from the randomly generated road surface. The dynamic responses of various bridges designed according to current design practice are examined, in which important structural parameters(such as span length, girder spacing, etc.) are considering systematically. In addition, the traffic conditions of multi-truck traveling either consecutively on the same lane or side-by-side on the adjacent lanes are also evaluated.

• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2006.09a
• /
• pp.566-567
• /
• 2006

The characteristics of residual stresses occurring in PM steel based nickel (FLN2-4405) was investigated. The measurements of residual stresses were carried out by electrochemical layer removal technique. The values and distributions of residual stresses occurring in PM steel processed under various densities and heat treatment conditions were determined. In most of the experiments, tensile residual stresses were recorded in surface of samples. The residual stress distribution on the surface of the PM steels is affected by the heat treatment conditions and density. Maximum values of residual stresses on the surface were observed sinter hardened condition and $7.4\;g/cm^3$ density. Minimum level of recorded tensile residual stresses are150 MPa and its maximum level is 370 MPa.

• Journal of Microbiology and Biotechnology
• /
• v.22 no.7
• /
• pp.923-929
• /
• 2012

Optimization of culture conditions for L-asparaginase production by submerged fermentation of Aspergillus terreus MTCC 1782 was studied using a 3-level central composite design of response surface methodology and artificial neural network linked genetic algorithm. The artificial neural network linked genetic algorithm was found to be more efficient than response surface methodology. The experimental $_L$-asparaginase activity of 43.29 IU/ml was obtained at the optimum culture conditions of temperature $35^{\circ}C$, initial pH 6.3, inoculum size 1% (v/v), agitation rate 140 rpm, and incubation time 58.5 h of the artificial neural network linked genetic algorithm, which was close to the predicted activity of 44.38 IU/ml. Characteristics of $_L$-asparaginase production by A. terreus MTCC 1782 were studied in a 3 L bench-scale bioreactor.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.20 no.10
• /
• pp.9-18
• /
• 2021

The cutting force in a cutting simulation is determined by the cutting conditions, such as cutting speed, feed rate, and depth of cut. The cutting force changes, depending on the material and cutting conditions, and is affected by the heat generated during cutting. The physical properties for predicting the cutting force use constitutive equations as functions of the hardening term, rate-hardening term, and thermal-softening term. To accurately predict the thermal properties, it is necessary to accurately predict the thermal-softening coefficient. In this study, the thermal-softening coefficient was determined, and the cutting force was predicted, using the response-surface method with the cutting conditions and the thermal-softening coefficient as factors.

• Journal of Welding and Joining
• /
• v.14 no.2
• /
• pp.57-64
• /
• 1996

In this paper, authors are trying to find optimum spot weldig conditions to minimize indentation of the plate surface which is crucial to quality of stainless rolling stocks. At first, to derive a simple equation to estimate the depth of indentation, a simplified one-dimensional bar model is proposed and validity of the model is confirmed by experiments. And also, to find proper welding conditions giving satisfied tensile strength of the welded joint, a simple formula is derived referring to the standard spot welding conditions by AWS. Optimization problem is formulated to find welding conditions such as welding current, time and applied force which give minimum indentation and proper tensile strength of joint, and solutions are found out. According to the results, the depth of indentation can be expressed by applied electrode froces and it can be shown that an optimum applied force exists.

• Journal of Mushroom
• /
• v.19 no.2
• /
• pp.81-87
• /
• 2021

Roridin E, produced by Podostroma cornu-damae, is a mycotoxin with anticancer activity. To increase the content of roridin E, submerged culture conditions were optimized using response surface methodology. Three factors, namely, medium initial pH, incubation time and agitation speed were optimized using a Box-Behnken design. The optimum submerged culture conditions to increase the content of roridin E included a medium with an initial pH of 4.0, an incubation time of 12.90 days, and an agitation speed of 63.03 rpm. The roridin E content in the submerged culture, under the aforementioned conditions, was 40.26 mg/L. The findings of this study can help lower the current price of roridin E and promote its related research.