• Proceedings of the KSME Conference
• /
• 2008.11a
• /
• pp.1103-1106
• /
• 2008

For the current display process, the innovative micro pattern fabrication process using semiconductor process should be developed, which requires the expensive equipment, the limited process environment and the expensive optic-sensitive material. The effort of process innovation during past several years ends up the limit of cost reduction. The existing ink jet technologies such as a thermal bubble ink jet printing and a piezo ink jet printing are required to shorten the nozzle diameter in order to apply to the micro pattern fabrication. In this paper, as one way to cope these problems the micro pattern equipment based on the electrostatic ink jet has been developed and carried out some experiments.

• Fashion & Textile Research Journal
• /
• v.2 no.5
• /
• pp.411-415
• /
• 2000

To be able to work safely and efficiency, the Threshold Limit Values (TLV) for work in the heat are widely used. Since these TLV are only applicable to workers in regular clothing, TLV should be adjusted when applied to the asbestos removal workers who wear extra impermeable protective clothing. Although abbreviated guidelines for heat stress exposure have been proposed, literature advocating their use in the asbestos removal industry is limited. Therefore, we planed a survey to evaluate the workload of asbestos abatement workers in summer, and an experiment with climatic chambers to evaluate the effects of resting in a cool environment between work periods. From these studies, we got following conclusions. There is a high risk of suffering from heat illness by asbestos abatement work in summer in Japan. It is proposed to create a cool room inside the workplace of asbestos abatement work to reduce thermal stress.

• Proceedings of the KIEE Conference
• /
• 2002.07c
• /
• pp.1455-1457
• /
• 2002

The real-time dynamic rating system(DRS) can provide the maximum ampacity within required periods, so it can help the transmission-line operation more safely and efficiently. Because the conductor temperature is the main limit of increasing rating current, conductor temperature monitoring(CTM) technology is the basic to DRS. In this paper, real-time CTM was developed for 345kV XLPE cable in tunnel and we have also compared the CTM result of this study with the result according to IEC 287 and JCS 168 thermal parameters.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.5 no.2
• /
• pp.94-110
• /
• 1997

In the present study, a mean torque predictive model has been proposed and experimentally validated. It includes induction air mass model, fuel delivery model and mean production mode. Air induction and fuel delivery model considering dynamic behaviors of air induction and fuel delivery were proposed to predict the air-fuel ratio excursions under transient condition. Torque function model reflects thermal efficiency, volumetric efficiency, friction and effect of spark timing. In the spark timing model, knock limit and acceleration retard are included. Experiments were carried out to validate the simulation model for the step changes of throttle at constant engine speed. The results show reasonable agreements between simulation and experiment at fully warmed condition. Using this model, fueling strategies are varied with fast throttle open and it can predict air-fuel ratio excursion and IMEP.

• Korean Journal of Optics and Photonics
• /
• v.4 no.3
• /
• pp.354-358
• /
• 1993

The temperature distribution inside a zigzag slab laser glass was measured using a Mach-Zehnder interferometer. The temperature difference between the center and the surface of the slab caused the fracture of the slab glass. Two laser glasses were fractured at a temperature difference ${\Delta}T_0$of TEX>$110^{\circ}C$, $62^{\circ}C$ respectively. For the design of high-average power glass laser, it is recommended that the limit of the temperature difference ${\Delta}T_0$ inside the slab glass should be smaller than $50^{\circ}C$ for safe operation.ration.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.10a
• /
• pp.750-753
• /
• 2002

At present, almost circuits are wired using copper in flexible circuits. But, these circuit have limit to flexibility so it occurs fracture about cyclic bending and, thermal load of bending stress occur a circuit trouble. a study of all-polymer flexible circuits get over that problem. Established fabrication method of all-polymer circuits is photolithograph. This method can not have mass production, so this method wastes time and human effort. In this study, all polymer flexible circuits are fabricated using the inkjet process.

• 전기의세계
• /
• v.18 no.2
• /
• pp.7-14
• /
• 1969

From the first customer located right at the substation to the last customer at the end of the line, voltage must be held within close limits, so the voltage regulation is more important than the thermal limit. On a typical distribution system during the peak load period, the voltage drop may be serious enough to cause unsatisfactory operation of home appliances in the residential area, and present many problems to manufacturing industries, where the voltage must be maintained within close limits to insure smooth operation. Among all the factors contributing to voltage drop in the distribution system, the voltage drop in the distribution transformer may account for 30% of this figure. If we can eliminate this factor, the power companies can provide better quality electricity to more customers with the existing distribution facilities, thus saving on initial investment costs. Taking all these problems into consideration, the author undertook the design of a capacitive transformer which would give zero voltage drop at rated load and at 80% lagging power factor while incorporating overload features to withstand 400% overload for at least 100 seconds. The following are the results obtained through design, manufacture and test of an initial experimental transformer built with these specific purposes.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.22 no.11
• /
• pp.812-819
• /
• 2010

Recently residential buildings are characterized with high-rise and high density. Under this circumstance, achieving comfortable and healthy indoor environment with minimized energy consumption becomes a very challenging engineering and societal issue. Along this the increased size and transparency of window as well as light surface caused by high stories lowers the heat shield efficiency of building. Since glass that constitutes building surface has low heat efficiency, it aggravates heat loss of all building considerably, thereby resulting in extreme heating load and cooling load in the country where temperature varies much in summer and winter. The research will check whether experiment can be effectively done by overcoming the limit of existing artificial solar laboratory constructed in the country and properly adjusting controlled variables with simplified function through construction of this experimental set.

• Journal of the Korean Society for Railway
• /
• v.8 no.1
• /
• pp.57-62
• /
• 2005

The frost heaving pressure can be a problem for weakening of the railway roadbed material. This study was initiated to investigate the soils frost heaving pressure and physical characteristics(Liquid limit, permeability, SEM analysis) resulting from freezing and freezing-thawing cycle process. Therefore, upon freezing a saturated soil in a closed-system from the top, a considerable pressure was developed. Weathered granite soils, sandy soil were used in the laboratory freezing test which sometimes subjected to thermal gradients under closed-systems. The frost heaving pressure arising within the soil samples and the temperature of the samples inside were monitored with elapsed time. The degree of saturation versus heaving pressure curve is also presented for weathered granite soil and the maximum pressure is closely related to this curve. Based on the laboratory test results, fine-grained soils with strong attractive forces between soil grains md water molecules, and additional water is attracted into the pores leading to further volume changes and ice segregation.

• Journal of Mechanical Science and Technology
• /
• v.15 no.11
• /
• pp.1555-1562
• /
• 2001

In a conventional shell-and-tube heat exchanger, fluid contacts with tubes flowing up and down in a shell, therefore there is a defect in the heat transfer with tubes due to the stagnation portions . Fins are attached to the tubes in order to increase heat transfer efficiency, but there exists a limit. Therefore, it is necessary to improve heat exchanger performance by changing the fluid flow in the shell. In this study, a highly efficient shell-and-tube heat exchanger with spiral baffle plates is simulated three-dimensionally using a commercial thermal-fluid analysis code, CFX4.2. In this type of heat exchanger, fluid contacts with tubes flowing rotationally in the shell. It could improve heat exchanger performance considerably because stagnation portions in the shell could be removed. It is proved that the shell-and-tube heat exchanger with spiral baffle plates is superior to the conventional heat exchanger in terms of heat transfer.