• 제어로봇시스템학회:학술대회논문집
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• 1987.10a
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• pp.780-785
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• 1987

The measuring point data of clay model are widely used to design parts whose external features are important design factor such as automobiles and general die products. This paper presents a method for improving the process to generate smooth surfaces from the measuring point data using turnkey CAD/CAM system. The process of smooth-surface generation involves several steps: styline finding, curve fairing, surface generation and filleting. The process is improved by automatic curve fairing, local correction of surface and multi-boundary surface treatment. An automobile bumper and a telephone receiver are measured and modeled to test the new method. Significant time saving is resulted by changing interactive mode to automatic mode and eliminating inefficient loop of surface generation process.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.6
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• pp.592-600
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• 2010

The problem of motion control for AUV (Autonomous Underwater Vehicles) is addressed. The utilization of such robotic vehicles has gained an increasing importance in many marine activities. In this paper the objective is to describe how to design and apply FGS (Fuzzy Gain Scheduling) PD (Proportional Derivative) controller for an AUV (Autonomous Underwater Vehicle) to control the yaw and depth of the vehicle by keeping the path of the navigation to a desired point, and/or changing the path according to a set point.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.1
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• pp.35-44
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• 2015

This paper deals with the economic analysis of domestic fuel cell vehicles considering subsidy and hydrogen price in 2015 and 2025. We selected TFCV (Tucson fuel cell vehicle) and TDV (Tucson diesel vehicle) to identify the economic feasibility of fuel cell vehicles compared with conventional internal combustion engine vehicles. We made some sensitivity analysis by changing input factors such as the size of the subsidy, the hydrogen price and the discount rate. Also, we made a break-even point analysis on hydrogen prices that equalize the economic feasibility of TFCV and TDV in 2025. As a result, TFCV is not economical in 2015 due to the relatively high prices of hydrogen and vehicles. If the sale prices of TFCV are 30,000,000 won and 35,000,000 won in 2025, then the break-even points of hydrogen prices are equal to 7,483 won/kg and 5,043 won/kg.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1212-1218
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• 2003

A novel loading mechanism of wedge roller type has been developed. This type traction drive has long system life and high efficiency by changing the pre-load on a contact point. And this loading mechanism does not need precision machining. So it has, as opposed to the conventional loading mechanism, an advantage in saving manufacturing cost. In this paper, by analyzing pre-load generating mechanism, spring pre-load and the roller size are defined and the stress on the contact point by pre-load is calculated. On the basis of this analysis, the model of wedge roller type traction drive for the test is made and was carried out its performance test. It can transmit input torque up to 1.5 N m, with high efficiency over 91% up to 98%, with slip rate under 2.5%.

• Journal of the Korean Society for Precision Engineering
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• v.9 no.3
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• pp.117-121
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• 1992

There have been many studies on chatter vibration in machining but there seems to be no regulations to decide the commencing point of chatter objectively. The development of an objective method which can estimate and detect chatter commencement is very much in need for automatic manufacturing systems, dynamic performance tests for machine tools, and so on. In this study, an approach for in-process monitoring and for deciding commencing point of the chatter vibration using the frequency band-energy method was proposed. From this method, in-process monitoring system for detection the chatter vibration was developed, and investigated its practical possibility. As a result, it is shown by experiments that the chatter vibtation can be detected accurately. Since the changing pattern of the signal energy in certain frequency band during chattering is seldom affected by the variation of cutting conditions, if adequate pre-measures are taken, this method can be widely used in most machining processes.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.9
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• pp.27-35
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• 1994

It is known that a unified phase I-phase II semi-infinite optimization algorithm with a steerign parameter performs better than the original unified phase I-phase II algorithm. In this paper, the effect of the steering parameter is analized and a new algorithm is presented based on the facts that when the point x is far away from the feasible region, reaching to the feasible region is more important than minimizing the cost functio and that when the point x is near the region, it is more efficient to try to reach the feasible region and to minimize the cost function concurrently. It is also important to consider the relationship between the feasible direction and the gradient of the cost function. Even though changing the steering parameter does not change the rate of convergence of the algorithm, it is shown from examples that given new algorithm is more efficient than the previous ones.

• Proceedings of the IEEK Conference
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• 2002.06e
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• pp.231-234
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• 2002

In this paper, we propose an efficient bias circuit for hearing aid using discrete BJT. The collector feedback bias circuit, widely used for the hearing aid, has a resister for negative feedback. As the resistor affects AC and DC simultaneously, it is quite difficult to adjust amplifier gain without changing DC bias point. The previous bias circuit also has weak point to be oscillated by the positive feedback of power noise if gain of hearing aid is high. In the proposed circuit, we can reduce the two weak points of the previous circuit by adding a resistor which is ${\beta}$ times larger than collector resistor between base of BJT and power supply.

• Journal of Advanced Marine Engineering and Technology
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• v.26 no.1
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• pp.132-137
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• 2002

Recently, impinging spray is used for atomization of diesel engine, but it bring on adhesion of fuel. Therefore, we studied about droplet behavior on high temperature plate changing the size of droplet, surface temperatures, and surface roughness of plate. In this study, We studied to confirm experimentally about mechanism of evaporation and ignition process of single fuel droplet. We observed evaporation time, evaporation appearance and ignition delay time by the photopraphs of 8mm video camera. Experimental results are summarized as follows: 1. The boiling point of fuel affect a evaporation and ignition process. 2. The surface roughness affect a evaporation time. 3. The ignition delay time relate to evaporation characteristic.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.31 no.2
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• pp.36-42
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• 2008

As competition shifts from being a company oriented one to a supply chain oriented, an effective SCM(supply chain management) becomes a necessary strategy for any successful businesses. But, it is not easy to form a successful SCM, because the individual desire of participants conflict with others. These desires affect the performance of SCM and cause waste of cost and time. Analyzing a supply chain of discount retailers, this paper eliminates idle time and improves the process with rearranging the reorder closing time(reorder point). For win-win strategy, this work reveals the reorder closing time is an important factor. It is possible to reduce cost and time on the entire SCM process by just changing the ordering time.

• The KSFM Journal of Fluid Machinery
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• v.11 no.3
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• pp.50-55
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• 2008

The diverter system is a key component in achieving a high accuracy liquid flow rate standard using a static gravimetric system with a flying start and stop method. The diverter is a moving device used to direct flow alternately along its normal course(by pass) or towards the weighing tank. The time needed for collection into the weighing tank is measured using a timer. So it is important to the diversion period is sufficiently fast and triggering point of timer which is determined the filling time. On this studies show that uncertainty of diverter system for changing diversion speed and triggering point was estimated in accordance with Guide to The Expression of Uncertainty in Measurement(ISO).