• Proceedings of the KIEE Conference
• /
• 1999.11c
• /
• pp.558-560
• /
• 1999

For the high-rise buildings, the effective use of the buildings heavily depends on the transportation system inside the buildings. For a long period of time, elevators have been the most effective means for moving people residing in the buildings. As the number of elevators in the building grows, it is very complicated to control and manage the elevator system effectively. Since it is almost impossible to find the accurate mathematical model for the elevator systems, the conventional analysis method using the approximated equations is prone to error. In this work, the elevator simulator for the high-rise buildings is developed to assess the accurate behavior of the elevator systems. This simulator can be used to analyze the performance of the given system, or to facilitate the design of the effective elevator systems for new buildings. In this paper, the structure of the simulator has been explained and the simulation results are presented.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2003.07a
• /
• pp.101-104
• /
• 2003

The real test panel with the $200{\mu}m$ discharge gap in a coplanar AC plasma display panel was investigated. The auxiliary electrode was placed between two sustain electrodes and used for providing wall charges and prime particle during sustain period. The luminous efficiency had the maximum value when the voltage of the auxiliary pulses was 20 ${\sim}$ 100[V]. The luminous efficiency of coplanar long-gap discharge with auxiliary electrode was 2.6 times as much as that of the conventional structure.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
• /
• 2000.04a
• /
• pp.75-80
• /
• 2000

We revisit the arrested Ekman boundary layer problem, using a fully non-linear numerical model with the subgrid dissipation modeled by the large eddy simulation method (LES). The main objective of this study is to find out whether the dynamic balance of the arrested Ekman boundary layer explained by MacCready and Rhines (1991) is valid for high Reynolds number. The model solution indicates that for high Reynolds number and low Richardson number flows, the density anomaly diffusion by near-wall turbulent action may become intense enough to homogenize completely the density structure within the boundary layer, in the direction perpendicular to the sloping wall. Then the buoyancy effect becomes negligible allowing a near-equilibrium Ekman boundary layer flow to persist for a long period.

• International Commerce and Information Review
• /
• v.12 no.4
• /
• pp.127-149
• /
• 2010

It is well known that FTA increases consumer welfare. However, it is difficult to analyze consumer welfare effects of FTA for item by item because of the difficulty in data collection. In this respect, this study aims at analyzing the types of increasing consumer welfares with item by item. According to the result of the study, there are five types of consumer welfare increased by FTA, and the items are like below: banana, kiwi, octopus, wine, and etc. However, it is hard for consumer to feel effects of FTA directly for several reasons. The problem of distribution structure of imported goods and, tariff reductions over long period are parts of the reasons to reduce the consumer wealfare effects. And the lack of consumer awareness about imported goods also reduces them. In order to promote FTA more efficiently, this study suggests that the government must improve the problems mentioned because consumer consent is essential element for further FTA promotion.

• Proceedings of the Korean Society of Marine Engineers Conference
• /
• 2005.06a
• /
• pp.1011-1015
• /
• 2005

Fully digital controlled 20-bit magnet power supplies have been developed and successfully tested for closed orbit correction of PLS(Pohang Light Source). The new digital power supply has used fiber optics for 25kHz switching of IGBT drivers, and implemented DSP, ADC, Interlock, DCCT cards in a compact 3U-sized 19" chassis. Input/Output low-pass filters suppress harmonics of 60Hz line frequency and switching frequency noise effectively. Overall performance of the power supplies have been demonstrated as +/- 2ppm short-term stability(<1 min), and +/- 10ppm long-term stability(<36 hours). All the existing 12-bit 70 power supplies for vertical correction magnets will be replaced with new digital power supplies during 2005 summer shutdown period. In this paper, we will describe the hardware structure and control method of the digital power supply and the experimental results will be shown.

• Journal of the Korean Institute of Educational Facilities
• /
• v.10 no.5
• /
• pp.23-33
• /
• 2003

It is important to estimate the capability for the facilities and the condition of schools continually and correctly because the structure's life is remained more longer through the effective building control and preservation. In accordance with above of that, it is required to understand the knowledge about all matters at the stage of management for educational facilities and establish the procedure of the facility management consistently. This research suggests the method, which remains consistent and objective and deals with the total functional degree by following ㄴthe way to systemize the management plan of the facility estimation. The functional estimation of the existing facilities will be useful to make an plan for repair, maintain and checking of them as well as be the standard for remodeling and the educational facility duration, including long period project for building mending.

• International Journal of Fluid Machinery and Systems
• /
• v.2 no.4
• /
• pp.418-425
• /
• 2009

A vertical bulb turbine unit with elbow type draft tube has been developed due to avoidance of complicated assembling and long standstill period at overhaul in comparison with conventional horizontal bulb turbine unit. Before designing the prototype vertical bulb unit, a hydrographic model test was carried out to establish the ideal design concept for this innovative generating unit. Froude similarity is not available for vortex occurrence. Consequently, an intake structure without air entraining vortices under all the flow conditions is developed, and it is confirmed that the surge wave at load rejection is not affected harmful influence for other constructions.

• Journal of Technology Innovation
• /
• v.10 no.2
• /
• pp.107-129
• /
• 2002

Expansion and enhancement of information and communication infrastructure can create a market closer to an ideal type for a perfect competition, utilizing a cyber space in the network (with the expanded usage of Internet and e-commerce) and it could be a market of a monopolistic form. The government can take one of the two approaches responding to this monopolization of the digital market. First, the government maintains laissez-faire policy since the monopoly cannot be maintained over a long period of time due to an increasing in the production, decrease in the price, profit resulting from this and rapid technology evolution. Second, the government can actively interrupt the monopolization of the digital market. Monopolization in a digital market can lead to a market failure. Unstable market structure and too much frequent merger and acquisition contribute to making the digital market very dynamic. Information goods exchanged in the digital market have the features of very low marginal cost required to copy the original product whereas its initial fixed cost is very high. This explains why the information products are not priced based on the existing marginal price determination principles and why companies producing them have various product sales strategies (price/product differentiation strategy, and other sales strategies).

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.16 no.2 s.107
• /
• pp.132-140
• /
• 2006

This paper investigates the characteristics of dynamic responses of floating structures with connections under sea wave loads. Direct method using higher order boundary element method (HOBEM) and finite element method (FEM) is adopted for numerical analysis. A 500 m-long and 250-m width very large floating structure (VLFS) with four units are considered in numerical analysis. Hinge connection and spring connection with various strength are considered as connection types. Displacements and stresses of VLFS according to the connection types are compared considering wave period and heading angle reduction.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2005.05b
• /
• pp.177-180
• /
• 2005

Decing agent with chloride promote frost damage of concrete structure in winter period. From the safetyside, however, it is difficult to stop using chloride. Therefore, the durable concrete is required from now on. In this paper, long-term freezing and thawing test was carried out using the freezing water containing $CaCl_{2}$ to consider the concrete scaling according to the kind of binders, such as OPC, Flyash, Slag+Fa. and Slag As a result, it was found that the degree of scaling is different with containing slag being considered to prevent the penetration chloride ion and according to each binders.