• Proceedings of the KIPE Conference
• /
• 1999.07a
• /
• pp.577-580
• /
• 1999

High power density on-board power supply is implemented by using flat transformer. In the high frequency switching converters, large leakage inductance increases the switching stress and duty cycle loss, which sometimes limits maximum switching frequency. The flat transformer is designed by using special core structure, which has very low profile and low temperature rise since the thermal loading is spread evenly over a larger area. 100W, 3.3V output on board supply is built and tested and 50.7W/$\textrm{inch}^{3}$ power density is achieved.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.47 no.1
• /
• pp.1-9
• /
• 2015

Wood fibers for medium density fiberboard (MDF) was used in the filler layer of the white duplex board for increasing thickness and bulk of the board. The MDF fibers were treated with ozone (3% based on dry weight of the fibers), and mixed together with OCC (old corrugated container) to form paper. Ozone-treated MDF fibers gave high bulk, high tensile strength, high internal bond and fast drainage to the furnish mixed with OCC. It was shown that there were possibilities to reduced basis weight of the filler layer without loss of thickness, stiffness, and tensile strength. Furthermore, it showed the possibility to develop a new kind of board product that has high stiffness as well as high strength properties with light basis weight by application of the ozone-treated MDF fibers.

• Proceedings of the International Microelectronics And Packaging Society Conference
• /
• 1999.12a
• /
• pp.155-162
• /
• 1999

A bare chip packaging technology by an encapsulated flip chip bonding on a build-up printed circuit board has emerged in 1991. Since then, it enabled a high density and low cost semiconductor packaging such as a direct chip bonding on mother board and high density surface mount components, such as BGA and CSP. This technology can respond to various requirements from applications and is considered to take over a main role of semiconductor packaging in the next decade.

• Journal of the Korean Wood Science and Technology
• /
• v.31 no.3
• /
• pp.17-23
• /
• 2003

As a fundamental study of developing sawdust board from thinning softwood logs from three species (Pinus densiflora S. et Z., Larix leptolepis G. and Pinus koraiensis S. et Z.), this study examined the effect of board density and resin content on physical and mechanical properties of sawdust board. As the board density increase, thickness swelling, bending strength, and Brinell hardness increased while water absorption decreased. With increasing the resin content, the bending strength and hardness increased while water absorption and thickness swelling decreased. The board made of L. leptolepis was slightly low in its water absorption, and the one made of P. koraiensis was a little high in its bending strength, while there was no definite difference between each kind of trees in their hardness values.

• Journal of the Korean institute of surface engineering
• /
• v.32 no.3
• /
• pp.289-296
• /
• 1999

The integration of the LSI has been greatly improved and the circuit patters on the LSI are becoming finer line and pitch. The high-density electronic packaging technology is improved. In order to realize the high-density packaging technology, the density of the circuit wiring of the printed circuit boards have also been more dense. The build-up process multilayer printed circuit board technology have a lot of vias, possibilities of the finer conductor wirings and have a freedom of capabilities of wiring design. The build-up process printed circuit boards have the wiring rules which are the pattern width: $100-20\mu\textrm{m}$, the via hole diameter: $100-50\mu\textrm{m}$. There three kinds of build-up processes as far materials and hole drilling. In this paper, the recent technology trends of the build-up printed circuit board technologies are described.

• Proceedings of the KIPE Conference
• /
• 2003.07b
• /
• pp.781-784
• /
• 2003

In this paper, high density on-board dc/dc converter using multi-layer PCB is proposed. Recently, the communication system wants power supply of open-frame, high density and low profile. So experimental converter was consisted of 3.3V/30A Quarter Brick size DC/DC Converter. To power height limit, coil of transformer, choke and circuits were consisted of multi layer PCB. Besides to improve of efficiency, made secondary synchronous rectifier Mosfet driving circuit. So total efficiency could be improved.

• Journal of the Korean Wood Science and Technology
• /
• v.48 no.2
• /
• pp.196-205
• /
• 2020

The purpose of this study was to investigate a method for improving the physical and mechanical properties of laminated board made from oil palm trunk (OPT). The effects of pretreating the lamina with heat-pressure and altering the lamina composition of the laminated board were investigated. The outer third of OPT in cross-section had high-density wood, while the underlying third had low to medium density. The hot press was applied to pretreat the lamina that had low to medium density. The lamina were 1.5 cm in thickness, 5 cm in width, and 65 cm in length. The hot press was applied at 2.94 MPa or 4.41 MPa at 150 ℃ for 60 minutes, and the target thickness of the lamina was 1 cm. The three layers of the laminated board samples were bonded with isocyanate adhesive at a glue spread of 300 g/㎡ and cold pressed at 0.98 MPa for 3 h. The laminated board samples were tested according to Japanese Agricultural Standard (JAS) 234-2003. The results showed that the densification of the inner lamina did not significantly affect the physical-mechanical properties of the laminated board produced. However, the laminated board made with high-density laminas for the outer layers fulfilled the JAS 234-2003 standard for the modulus of elasticity and the modulus of rupture.

• Journal of the Korean Wood Science and Technology
• /
• v.15 no.2
• /
• pp.99-104
• /
• 1987

Fiber mats were made at various density levels, using fibers from papermill sludge, ricestraw and various mixtures of the two. The paper mill sludges were collected from Moorim Papermill Co, and Jeonjoo Papermill Co. They were soaked in the liquid sulfur compounds, sulfur-tall oil and sulfurpolyester compounds, and made into fiber-reinforced, sulfur-based composition board. Under optimum conditions of fiber mat preparation and saturation with molten sulfur and modified sulfur, the Young's moduls of the manufactured tiber-reinforced composition board are superior to those of conventional wood-based composition boards. For example, the moduli of elasticity of the composition board made from papermill sludge, with a density of 0.40gm/$cm^3$, were greater than 1,400,000psi as compared 800,000psi for high density hardboard(1.28gm/$cm^3$). The modulus of rupture of the best reinforced composition board manufactured was over 9000psi, comparable to 6000psi of high density hardboard. The proposed Bryant and Lee's theory, "Modified Rule of Mixtures" can be applicable to the nonoriented and short fibrous composition board, when it was modified from "Rule of Mixtures" established by Paul an Jones, and supplemented by Smith and Cox's theory, In the Bryant and Lee's theory of $E_c=\frac{1}{3}aE_fV_f+bE_mV_m$, the constants "a" and "b" for the composition boards made from papermill sludge and the mixtures of ricestraw and the sludge were identified to be in the ranges of 3.29~3.54 and -2.47~-2.80 respectively.

• Journal of the Korean Wood Science and Technology
• /
• v.39 no.1
• /
• pp.60-67
• /
• 2011

A repeated impregnation and carbonization process was introduced to product high-density woodceramics using a resin impregnation board. The density profile were measured to further confirm morphologically and structurally occurred changes of one-time and two-time phenolic resin-treated and carbonized woodceramics. After the two-time carbonization of the products, the minimum, average and maximum densities increased more than those of the one-time carbonized woodceramics, and the increase of density profile. Therefore, it is considered that the preparation of uniformed woodceramics with high-density and low density dissipation can be produced by a repeated impregnation and carbonization).

• The Transactions of the Korean Institute of Power Electronics
• /
• v.22 no.6
• /
• pp.510-516
• /
• 2017

This paper proposes a single-stage interleaved totem-pole on-board battery charger with a simple structure and a reduced component count. Apart from achieving ZVS turn-on of all switches and ZCS turn-off of all diodes, this charger does not require an input filter due to its CCM operation and bulky electrolytic capacitors, which in turn result in a high power density. A single-stage power conversion technique is applied to the interleaved structure in order to achieve a high power density and high efficiency. A 2.5 kW prototype of the proposed charger is also built and tested to validate the proposed operation.