• Journal of Advanced Marine Engineering and Technology
• /
• v.16 no.5
• /
• pp.6-16
• /
• 1992

Since world-wide oil shock on 1970s, many large size-low speed diesel engines, instead of steam turbines, are used for the industrial electric power generating plants due to their economic advantage of low specific fuel consumption. But it is very important to control their electric power fluctuation problems for the purpose of smooth parallel operation with existing power plants. In this paper the fluctuation problem of KEPCO Nam-cheju No.1 generator driven by diesel ngine(B & W 7K 60MC, 13931x138.5RPM) is investigated with analysis of torsional vibration of which 4th harmonic component is related to its power fluctuation. The problem can be improved by modification of cylinder arrangement and flywheel position in reverse sequence, equalizing the combustion gas pressure of all cylinder and installation of torsional vibration damper enlarged 30%(Je=7287Kg.m$^{2}$) and high quality balancing of generator rotor.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2000.11a
• /
• pp.838-841
• /
• 2000

To improve the accuracy of products and improve the product quality, we need to enhance the machining accuracy of the machine tools. To this point of view, measurement and inspection of finished part as well as error analysis of machine tools has been studied for last several decades. OMM(On the Machine Measurement) has been issued to alternate with CMM, pointing out disadvantages of high expenses and lots of setting time in CMM. In this paper, we study 1) the spherical surface manufacturing by volumetric error compensation of machine tool, 2) the system development of OMM without detaching work piece from a bed of machine tool after working. 3) the generation of the finished part profile by On the machine measurement. Furthermore, the output of OMM is compared with that of CMM, and verified the feasibility of the measurement system.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1997.04a
• /
• pp.327-331
• /
• 1997

As demand for various kinds and small lot products has been increasing, batch annealing has been appreciated for its small restiction for the opteration. The cold spot of the coil is very important in the BAF(Batch annealing furnace) annealing process. Because of the annealing cycle time in the BAF, annealing was decided on the cold spot of the coil. So, we tested the effect,variation of cold spot, for hydrogen contents of atmospheric gas at the annealing furnace. As a result of several investigations. We confirmed the following characteristics ; after the heating and soaking,the cold spot of coil moved to 1/3 of coil thickness in the NHx atmospheric gas, but the mid point of the coil thickness is the cold spot in the Ax or .H/sub2. atmospheric gas. Therefore, the use of hydrogen instead of nitrogen as the protective gas,combined with high convection in batch annealing furnaces, has shown that considerable increases in furnace output and material quality are attainable. Owing to the low density, high diffusion and reducing character of hydrogen, a better transfer resulting in uniform material temperatures and improved coil surfaces can be achieved.

• Proceedings of the Korean Society of Marine Engineers Conference
• /
• 2006.06a
• /
• pp.71-72
• /
• 2006

This paper introduces the results of the development of a new mobile Digital DC-arc Welding Machine (DDWM). A simple PI controller is applied to the DDWM to control the output welding current tracking the constant setting current. Furthermore, a hot-start function, an anti-stuck function, a standby mode and an intelligential circuit breaker (ICB) are included in the DDWM. The DDWM increases welding quality and saves more power energy than a conventional welding machine. Because the DDWM is changed from ready mode into the standby mode automatically after 2 minutes interval from this unload start. Then the DDWM is changed into ready mode automatically since it is reused to weld. Mover, the DDWM increases welding qualify, productivity and reduces costs of welding. So, the DDWM can have a great of contribution to the mobile welding industries. The effectiveness of the DDWM was proven by the experimental results and durable test.

• Proceedings of the Korean Society of Medical Physics Conference
• /
• 2002.09a
• /
• pp.302-304
• /
• 2002

In linac-based stereotactic radiosurgery, assuring the quality of the planning and delivery of external photon beam requires accurate evaluation of beam parameters, usually including output factors, tissue-phantom ratio and off-axis ratios, and measurement of actual dose distributions from simulated treatment. We're going to test the use of calibrated radio chromic film (Gafchromic film; type MD-55, Nuclear associate) using a Lumiscan 75 digitizer to measure absolute dose and relative dose distributions for linac-based radiosurgery unit Relative dose distribution of a human-style spherical acryl phantom were measured using radiochromic film and calculated by treatment planning system. The absolute dose at the sphere center was measured by radiochromic film and micro chamber (Exradin A-14, 0.009cc). What we want to demonstrate in this work, the 'well selected' radiochromic films when external photon beam are used in linac-based stereotactic radiosurgery are very accurate detector for dosimetry.

• Journal of Power System Engineering
• /
• v.10 no.2
• /
• pp.36-40
• /
• 2006

In order to prevent the environmental pollution, the dryers are commonly used to treat sludge that one of sewages is polluting the quality of water. Generally, the drying method is various as to the property of material and use. Rotary dryer is a good apparatus to treat them. It is the way that is to make substance transmission and heat using hot air between sludge particle and heated gas. In this paper, we developed a 3-pass rotary dryer for a design program for the 3-pass rotary dryer with various conditions. The working conditions of dryer are a raw sludge feed rate, input & output water content and operation time etc.

• Architectural research
• /
• v.13 no.3
• /
• pp.49-56
• /
• 2011

Competitive bidding in construction is concerned with contractors making strategic decisions in respect of determination of bid price if contractors opt to bid. This study presents a strategy model for deciding optimum tender price with reflecting appropriate profit in competitive bidding using Bayesian regression analysis (BRA). The purpose of the developed model is to help contractors to secure suitable profitability by predicting the actual profit based on key variables. They may affect construction cost at bidding phase, ultimately which help contractors to secure high quality output. The model was tested empirically by application to a bidding dataset collected from a large South Korea contractor. BRA allows contractors to estimate more accurate actual profit by reflecting not only objective information but also subjective experiences and judgments. Consequently, the model can contribute to improvement of decision-making process for setting an optimum tender price.

• Journal of the Korean Institute of Telematics and Electronics B
• /
• v.31B no.4
• /
• pp.88-96
• /
• 1994

In this paper, we propose a subband pyramid image coding scheme that uses ECVQ (ntropy Constrained Vector Quantizer). In subband pyramid image coding, each subband can be encoded with a coder matched to the statistics of that particular subband, and available versions of the original image at different resolution are easily obtained. ECVQ, aiming at the minimization of the distortion for a fixed entropy of the quantizer output, is well combined with the subband pyramid image coding which yields high compression ratio and good image quality. The optimum bit allocation to each subbands corresponds to the points where the individual distortion rate curves are of particular slope, weighted to the number of samples in that subband, in designing ECVQ.

• Proceedings of the KSR Conference
• /
• 2010.06a
• /
• pp.2040-2047
• /
• 2010

Railway system which has latent loss of lives and property by big accident with that human error such as locomotive driver, manager, signaller, and the others involved. So human error management is needed to control this complex system and to confirm safety of it. Rail human error research for managing human resource has grown rapidly in both quantity and quality of output over the past few years. The continual influences of safety concerns, new technical system opportunities, reorganization of the business, needs to increase effective, reliable and safe use of capacity, and increased society, media and government interest have now accelerated rail human factors research programmes in several countries. The objective of this research is to improve safety and to reduce accidents in korean railway system, through the application of research results to the investigation of requirement for human error.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.19 no.37
• /
• pp.53-61
• /
• 1996

Recently the business transformaton of a company is achieved through the business process re-design and total quality management concept. This paper focused on the decision of the critical measurement point(CMP) for maximizing the effectiveness of the business process reengineering. In general, the types of business processes can be classified into two kinds, serial processes with IPO(input/process/output) type and non-serial processes with workflow type. The traditional method of selecting the CMP relies on the experiences and intuitions of the process owners. We suggest a mathematical method for more objective selection of CMP by using Dynamic Programming.