• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.24 no.12
• /
• pp.3026-3032
• /
• 2000

To enhance the effective data transfer rate the multi-beam optical disk drive is presented. The Beam rotating actuator is necessary for putting multi-beam on more than one track. Ray tracing was also executed for real system set-up. The beam Rotating Actuator is made up of piezoelectric material, high stiffness wire hinge and dove prism. The actuator has about 1kHz natural frequency and suitable operational range. The dynamic equation for the actuator is derived for the control real system.

• The Journal of Korean Association of Computer Education
• /
• v.14 no.6
• /
• pp.83-89
• /
• 2011

In this study a smart HDMI switch is proposed to detect newly formed video stream and automatically change the transfer path to the corresponding port without pulling the HDMI plug and putting it again in the desired port manually and physically. Furthermore the proposed switch is designed in the advanced wireless video transmission scheme based on millimeter band technology. The proposed system shows its feasibility by the hardware experiment in the full-HD video transmission performance including the function of the smart port change.

• 한국전산유체공학회:학술대회논문집
• /
• 2006.05a
• /
• pp.35-40
• /
• 2006

The insatiable desire of consumers to want more and more performance from computer equipment has driven the powers of this equipment to levels that are putting a strain on the thermal management of data centers housing this equipment. Equipment powers have been rising steadily over the past 10 years at a rapid rate. When the industry switched from bipolar to CMOS back in the early 90's industry experts had thought that the low power CMOS technology would resolve all problems associated with power and heat. Little did they know that now the problems associated with the CMOS equipment has surpassed anything installed with the bipolar technologies 10 to 15 years ago. Data centers are being designed with 15 to 20 years life spans and customers we asking how to plan for the power and cooling within these data centers. This paper addresses some of the current issues with cooling of equipment in data centers and describes some of the on-going efforts to under the thermal environment. To set the stage far describing the data center thermal management issues the power trends from the microprocessor to the rack will be described.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2012.05a
• /
• pp.137-138
• /
• 2012

Domestic construction materials market was about 65 trillion won and it occupied 45% level of total construction cost by 2007. In addition, due to the recent rapid rise of crude oil and iron ore price, fluctuation of raw material cost has a great influence to the cost of construction industry. This means that smooth performance is closely related to construction materials. And among them, because of high putting rate of metal materials, it can be seen that the fluctuation of metal material prices is an important variables. So in this study, for the pre-study to analyze the impact of metallic material prices to construction cost, the researcher analyzed a causal relationship between metal material prices and construction cost.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2016.05a
• /
• pp.93-94
• /
• 2016

The resistance of crowd pressure is an important performance to be influential on safety of facility users among performances required for light weight walls of public facilities. This study has empirically evaluated the estimation of size of crowd pressure to be applied to a wall of structure. For the load analysis test, the force plate with stiffness of 28 kN/cm was designed and manufactured. For inspectors, 15 males in the age of 20s were selected. The action of putting load was set as instantaneous push of plate and continuous push. As the load was increased linearly from the weight of inspector, the size of load was indicated as the load ratio. In case of instantaneous force, about 1.18 times the weight of pushing personnel was acted as a load. In case of continuous push, about 0.80 times the weight of pushing personnel was acted as a load.

• The Journal of the Korea Contents Association
• /
• v.6 no.11
• /
• pp.276-284
• /
• 2006

WRR scheme was developed for scheduling scheme for guaranteeing bandwidth requirement. In these days, WRR scheme can handle multiple queues straightforwardly by putting a different weight on each queue in order to offer differentiated services such as different bandwidth or delay bound in wireless communication network. Also, WRR algorithm can be implemented efficiently by dynamic binary scheduling wheel(DBSW) architecture. This paper performs the mathematical analysis of the DBSW architecture and compares the results with simulation results. The analysis data and simulation data show that the mathematical analysis developed properly.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2014.11a
• /
• pp.65-67
• /
• 2014

There are many elastomeric joint sealant applications in construction such as structural glazing, weatherproofing and insulating glass fabrication etc. Each sealant joints require unique durability functions to perform well through building life cycle. Elastomeric joints in bathroom and kitchen is one of areas which require durable sealing. In this application, anti fungal durability is proprietary function of sealant during building life cycle. Premature failure of anti fungus resistance of sealant is putting big stresses to general contractor as well as the inhabitants due to costly rework and poor sanitation. Accordingly, when chemists design a product, they must take into account various parameters not only formulation components also test conditions in order to have long term fungal durability. This paper reviews several biocide options with various industry standards for fungus resistance performance to suggest making new test method for construction sealant industry.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.39 no.3
• /
• pp.254-262
• /
• 1990

In the active power filter, the PWM method for controlling the power converter plays an important role for the performance and the efficiency of the filter. In this paper, a new PWM method for the single phase current source type active power filter is presented, which is intended particularly for obtaining the maximum efficiency of the compensation. This method is basically based upon the optimized injection method, but in contrast to the existing method, this method adapts the optimized injection method by putting not only the pulse width, but also the pulse position into control variables. By doing this, when the number of pulses per one cycle is N, lower order harmonics up to the Nth order can be completely eliminated by the filter. So, this method is much more efficient than any other existing method. These characteristics are well verified by the computer simulations and the experiments.

• Structural Engineering and Mechanics
• /
• v.27 no.2
• /
• pp.149-172
• /
• 2007

An experimental study of five full-scale coupling beam specimens has been conducted to investigate the seismic behavior of strengthened RC coupling beams by bolted side steel plates using a reversed cyclic loading procedure. The strengthened coupling beams are fabricated with different plate thicknesses and shear connector arrangements to study their respective effects on load-carrying capacity, strength retention, stiffness degradation, deformation capacity, and energy dissipation ability. The study revealed that putting shear connectors along the span of coupling beams produces no significant improvement to the structural performance of the strengthened beams. Translational and rotational partial interactions of the shear connectors that would weaken the load-carrying capacity of the steel plates were observed and measured. The hierarchy of failure of concrete, steel plates, and shear connectors was identified. Furthermore, detailed effects of plate buckling and various arrangements of shear connectors on the post-peak behavior of the strengthened beams are discussed.

• School Mathematics
• /
• v.2 no.1
• /
• pp.73-95
• /
• 2000

In this study, on the basis of the seventh national mathematics curriculum, the achievement standards were developed to specify the objectives and contents of teaching-learning at the first and second elementary school mathematics. The assessment standards were also developed to differentiate students’ levels of achievement with ‘high’, ‘mid’ and ‘low’ categories. Furthermore, this stuffy suggested the exemplary test items including short-answer and open-ended questions while putting emphasis on students' real performance to increase their ability in solving problems rather than in calculating. In addition to the test items, it introduced the grading system developed to grade the items with concrete guidelines and to report students' achievement on doing mathematics.