• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.5
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• pp.101-106
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• 2006

This paper describes performance design of a solid rocket motor on which thrust cut-off system is installed, and evaluates performance of a rocket motor according to a size of TCO ports. TCO system installed on motors was made to carry out firing tests, and the trend of thrust due to various sizes of TCO port was analyzed to find the existence of the port size for maximum reversal thrust. Conservation equations were used to design performance of motors and to analyze test results. This technique for performance design will be usefully applied to the design of similar TCO systems.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.53-56
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• 2006

This paper describes performance design of a solid rocket motor on which thrust cut-off system is installed, and evaluates performance of a rocket motor according to a size of TCO ports. TCO system installed on motors was made to carry out firing tests, and the trend of thrust due to various sizes of TCO port was analyzed to find the existence of the port size for maximum reversal thrust. Conservation equations were used to design performance of motors and to analyze test results. This technique for performance design will be usefully applied to the design of similar TCO systems.

• Ocean and Polar Research
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• v.26 no.2
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• pp.265-272
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• 2004

This study was conducted to investigate the community structure and distributional pattern of meiobenthos in the deep-sea bottom of the Clarion-Clipperton Fracture Zone of northeastern Pacific during July 2001. Examination of sediment samples collected on the eight survey station showed that there were 10 different types of meiobenthos. The most abundant meiobenthic animals were nematodes in all stations. Sarcomastigophorans, benthic harpacticoids were next abundant meiobenthos. Vertical distribution of meiobenthic animals showed the highest individual numbers in the surface sediment layers of 0-1 cm depth and showed more steep decreasing trend as sediment gets deeper on the stations of high latitude located in $16-17^{\circ}N$. Horizontal distribution of meiobenthic animal in the study area within CCFZ showed high densities of meiobenthos at the stations had few manganese nodules on their sediment surface in the site of low latitude. For size distribution analyses showed that animals which fit into the sieve mesh size of 0.063 mm were abundant.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.359-361
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• 2006

As circuits become increasingly complex and devices sizes shrinks, the demands placed on global planarization of higher level. Chemical Mechanical Polishing (CMP) is an indispensable manufacturing process used to achieve global planarity. In the CMP process, Diamond Disk (DD) plays an important role in the maintenance of removal rate. According to studies, the cause of removal rate decrease in the early or end stage of diamond disk lifetime comes from pad surface change. We also presented pad cutting rate (PCR) as a useful cutting ability index of DD and studied PCR trend about variable parameters that including size, hardness, shape of DD and RPM, pressure of conditioner It has been shown that PCR control ability of pressure and shape is superior to RPM and size. High pressure leads to a decrease of cell open ratio of pad surface because polyurethane of pad is destroyed by pressure. So low pressure high RPM condition is a proper removal rate sustain. By examining correlations between RPM and pressure of conditioner, it has been shown that PCR safe zoneto satisfy proper removal rate has the range 0.06mm/hr to 0.12mm/hr.

• Particle and aerosol research
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• v.11 no.4
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• pp.93-98
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• 2015

Particles which generated from plasma enhanced chemical vapor deposition (PECVD) during thin film deposition process can affect to the process yield. By using light extinction method, ISPM can measure particles in the large-diameter pipe (${\leq}300mm$). In our research, in-situ particle monitor (ISPM) sensor was installed at the 300 mm diameter exhaust-line to count the particles in each size. In-house flange for mounting the transmitting and receiving parts of ISPM was carefully designed and installed at a certain point of exhaust line where no plasma light affect to the light extinction measurement. Measurement results of trend changes on particle count in each size can confirm that ISPM is suitable for real-time monitoring of vacuum process.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.8
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• pp.871-874
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• 2004

In recent, it is said that the trend of LCD is direction to pursue high qualities like as high transmittance, high contrast ratio, wide viewing angle, fast response time, and so on. Especially, it is known that these qualities are essential to large size LCD like as LCD TV and we can realize them through to uniform cell gap and deep black state. Until now, the ball spacer has been used to control of uniform cell gap. However, the existence of ball spacer inside the cell causes the deformation of the liquid crystal molecules and damage to alignment layer. Such a deformation of the liquid crystal causes light-leakage in the dark state, which lowers contrast ratio of the display. Nowadays, this problem has been solved by using Patterned Spacer on Color Filter. but Side Effect just as gravity mura has been induced. In this paper, we studied the mechanism on gravity mura in case of using patterned spacer on color filter.

• Journal of Mechanical Science and Technology
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• v.17 no.12
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• pp.2053-2065
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• 2003

The current trend in automotive finishing industry is to use more electrostatic rotating bell (ESRB) need space to their higher transfer efficiency. The flow physics related with the transfer efficiency is strongly influenced by operating parameters. In order to improve their high transfer efficiency without compromising the coating quality, a better understanding is necessary to the ESRB application of metallic basecoat painting for the automobile exterior. This paper presents the results from experimental investigation of the ESRB spray to apply water-borne painting. The visualization, the droplet size, and velocity measurements of the spray flow were conducted under the operating conditions such as liquid flow rate, shaping airflow rate, bell rotational speed, and electrostatic voltage setting. The optical techniques used in here were a microscopic and light sheet visualization by a copper vapor laser, and a phase Doppler particle analyzer (PDPA) system. Water was used as paint surrogate for simplicity. The results show that the bell rotating speed is the most important influencing parameter for atomization processes. Liquid flow rate and shaping airflow rate significantly influence the spray structure. Based on the microscopic visualization, the atomization process occurs in ligament breakup mode, which is one of three atomization modes in rotating atomizer. In the spray transport zone, droplets tend to distribute according to size with the larger drops on the outer periphery of spray. In addition, the results of present study provide detailed information on the paint spray structure and transfer processes.

• Journal of the Semiconductor & Display Technology
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• v.8 no.4
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• pp.53-58
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• 2009

A SMT mounter is a kind of equipment that mounts SMD parts quickly on the printed circuit board. By using linear motors, it is controlled with high speed and precision, which is similar to semi-conductor and display process equipment. It is necessarily used in an assembly process of an electronic device. Mobile devices such as a mobile phone and PDA are required to reduce mount areas due to the demands for high performance and small size. Hence, super small sized and complex mobile devices have been developed. To improve the productivity of the corresponding equipment, designs with large sized, high speed, and multidisciplinary functions have been consistently performed. Meanwhile, a design trend of large size and light-weight on SMT mounter causes a low natural frequency of systems and vibration problems at the high speed operation. In this paper, the dynamic characteristics of the SMD mounter system were investigated through a modal test and transmissibility test, and verified by finite element method. Also, various design improvement was performed to avoid the resonance phenomena.

• Tunnel and Underground Space
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• v.8 no.3
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• pp.194-199
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• 1998

This research was aimed to figure out the trend of dust diffusion at open pit limestone mine for assessing the environmental impacts on the high voltage power transmission line. It is rather easy to assess the dust generation and size distribution of limestone dust at the blasting site, but it is very hard to assess the expected area of dust diffusion and amount of dust fall by the distances from the dust source. In this research, a 3-dimensional fluid dynamic simulation software (3D-Flow) was used for analysing the above mentioned matters to assess the impacts to the insulators on the transmission tower by the blasting dust. It was verfied that the 3D-Flow is reliable tool for simulating dust movement, and the limestone dust is not much hazardous to the power transmission line.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.2
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• pp.355-360
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• 2007

The recent TFT-LCD Trend that is done large size gradually. As size of monitor great, though problem happens, it is that consumer's request which it makes monitor combined TV function. Monitor and TV are no difference externally greatly, but define difference happens as for backlight. An external electrode fluorescent lamp (EEFL) has an advantage of a long lifetime in the early stages of the study on plasma discharge, interest in the lamp continues. Researches on the operation of external electrode fluorescent lamps have focused mainly on its use of a type of high frequency (MHz). By performing high Luminance using a square wave operation method with the low frequency below 100kHz, which is applied to a narrowed tube type lamp that has several mm of lamp diameter, EEFL presented the possibility of using it as a light source for back-lights. However, because EEFL generates plasma using wall charges, which considers the impedance characteristics of glass based on the structural principle in discharge, it can be significantly affected by frequency. Thus, this study verified the change in the characteristics of electromagnetic fields according to the change in frequency through a Maxwell electromagnetic field simulation and examined the relationship between the change in the EEFL frequency and Luminance by measuring the optical characteristics.