• Journal of computational fluids engineering
• /
• v.5 no.1
• /
• pp.8-13
• /
• 2000

In this study, the spray models incorporated into the GTT code were tested for sprays injected in quiescent swirling gases and for the sprays impinging on a flat wall, and the validity of the models has been confirmed by comparing the calculated results with the experimental data. Using this code, the gas flow, spray behavior and fuel vapor distributions in the combustion chamber of a D.I engine have been numerically analyzed with respect to the constant injection pressure and the injection pressure varying with injection time.

• Fashion & Textile Research Journal
• /
• v.11 no.3
• /
• pp.465-468
• /
• 2009

In this study, acid cellulase was used to treat denim fabrics by varying pH, temperature, enzyme concentration, treatment time and non-ionic surfactant (Triton X-100) concentration. Treatment condition was controlled based on the weight loss. The characteristics of enzyme-treated fabrics were measured in terms of tearing strength, stiffness, and color difference. The optimum conditions for cellulase treatment of denim fabric were pH 5.0, $50^{\circ}C$, 3% (o.w.f.), 90minutes. The weight loss did not change significantly with the addition of a non-ionic surfactant, but it improved when more non-ionic surfactant were used. The tearing strength of enzyme-treated denim fabrics did not deteriorate. The stiffness of the treated fabrics improved with the enzymatic treatment with and without the non-ionic surfactant. The difference in color of fabrics treated with enzyme increased.

• 제어로봇시스템학회:학술대회논문집
• /
• 2000.10a
• /
• pp.228-228
• /
• 2000

To deal with non-linearities and time-varying characteristics of hydraulic systems, in this paper, the neuro-fuzzy controller has been introduced. This controller does not require an accurate mathematical model for the nonlinear factor. In order to solve general fuzzy inference problems, the input membership function and fuzzy reasoning rules are used for determining the controller Parameters. These parameters are determined by using the learning algorithm. The control performance of the neuro-fuzzy controller is obtained through a series of experiments for the various types of input while applying disturbances to the cylinder. .and performance of this controller was compared with that of PID, PD controller. As a experimental result, it can be proven that the position tracking performance of the neuro-fuzzy is better than that of PID and PD controller.

• Journal of the Korean Society for Precision Engineering
• /
• v.15 no.8
• /
• pp.33-38
• /
• 1998

TiYN coated high speed steel tools have been developed and their tool lifes were assessed. First yttrium alloyed titanium target was manufactured, then using the arc ion plating(AIP) technique TiYN coating was deposited onto high speed steel substrate. Three kinds of varying thickness of TiYN coated tools were prepared. Cutting tests were carried out with theses tools and for comparison with the commercially available uncoated, TiN, TiCN and TiAlN coated tools. During the cutting tests flank wear width vs. cutting time was measured. It has been revealed that the newly developed TiYN coated tools show superior tool life characteristics to others.

• Journal of the Korean Society of Industry Convergence
• /
• v.2 no.2
• /
• pp.165-172
• /
• 1999

Crane operation for transporting heavy loads causes swinging motion at the loads. This sway causes the suspension ropes to leave their grooves and leads to possibility of serious damages. Generally crane is operated by expert's knowledge. Therefore, a satisfactory control method to supress object sway during transport is indispensible. The dynamic behavior of the crane shows nonlinear characteristics. when the length of the rope is changed the crane is time varying system and the design of anti-sway controller is very difficult. In this paper, the nonlinear dynamic model for the industrial overhead crane is derived. and the feedback gain matrix based on the pole-placement method is proposed to supress the swing motion and control the position of the crane. The performance of the controller for the crane model is simulated on the personal computer.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.16 no.9
• /
• pp.1870-1877
• /
• 2012

Transient signals generally have short duration and variable length with time-varying and non-stationary characteristics. Thus frame-based pattern matching method is useful for classification of transient signals. In this paper, we propose a new method for classification of underwater transient signals using a Gaussian mixture model(GMM). We carried out classification experiments for various underwater transient signals depending upon the types of noise, signal-to-noise ratio, and number of mixtures in the GMM. Experimental results have verified that the proposed method works quite well for classification of underwater transient signals.

• Proceedings of the KSR Conference
• /
• 1998.05a
• /
• pp.502-509
• /
• 1998

The scheme to reduce jerking phenomena in one push-pull type trainset was proposed. To simulate the jerking between coaches, dynamic analysis model was made. This model could analyze longitudinal dynamic behavior between locomotives and coaches caused by spring and damping characteristics of couplers and center pivots; characteristic curves of traction and braking. To validate the analysis results, tests were conducted in the same driving and braking condition. Comparison of longitudinal acceleration between simulation and test results shows a good agreement. To minimize the jerking phenomena, lots of dynamic simulations were conducted with varying driving/braking effort curve. From the results of simulations, an efficient and economic way to reduce jerking phenomena was found to be to reduce slope of tractive effort curve and synchronize braking time between locomotives and coaches. Test results show that this way could reduce the jerking Phenomena. To express jerkins Phenomena quantitatively, maximum peak to peak values of acceleration were used.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
• /
• 2004.11a
• /
• pp.283-287
• /
• 2004

Arc welding is sometimes used to repair damaged cast iron parts in diesel engine for driving a ship. In this case cola arc welding. is good for. saving the time and results in good repairing. But if some difference in hardness on welding zones made with AWS E Ni-CI and NiFe-CI. happen, repaired parts would be cracked in a short. In order to overcome this default, the study is performed on varying preheating temperature of welding parts, selecting welding rod and welding work way. The result will be used on ship's repair working shop.

• Journal of Ocean Engineering and Technology
• /
• v.20 no.2 s.69
• /
• pp.41-45
• /
• 2006

Arc welding is sometimes used to repair damaged cast iron parts in diesel engine for driving n ship. In this case cold arc welding is good for saving the time and results in good repairing. But if some difference in hardness on welding zones made with AWS E Ni-CI and NiFe-CI happen, repaired parts would be cracked in a short. In order to overcome this default, the study is performed on varying preheating temperature of welding parts, selecting welding rod and welding work way. The result will be used on ship's working shop.

• Proceedings of the KIPE Conference
• /
• 2005.07a
• /
• pp.750-753
• /
• 2005

This paper presents a method of detecting rotor position for single phase Switched Reluctance Motors(SRMs) using searchs coil. In the single phase SRM, mainly Hall effect sensors or photo interrupters have been used to detect the rotor position. But these sensors cause high cost and increase the volume of the motor, Furthermore when the motor is used in very hostile environment like high temperature or pressure, its reliability goes down. In this paper, low cost and robust characteristics of rotor position detection method are focused in order to compensate for disadvantage of existing sensors. Search coils wound around the stator pole are used for detection of the rotor position in single phase SRM. Rotor position detection is achieved through electromotive force patterns induced by time-varying flux linkage in the search coil. The validity of the method is verified by experimental results.