• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 2004.05a
• /
• pp.632-635
• /
• 2004

PCB assembly is a complicated and difficult process to optimize due to the necessity of simultaneous consideration of rack assignment and board mounting sequencing. An efficient component mounting method is developed using component gathering phenomenon. It is found that same components are located closely each other by checking PCBs in field and interviewing PCB designers. A new method counting this phenomenon is developed and it is performed better with more number of total components and more number of gathered components cases. Simulation models are developed using Visual C++ for performance evaluation of the heuristic.

• Microbiology and Biotechnology Letters
• /
• v.24 no.6
• /
• pp.657-663
• /
• 1996

Pseudomonas sp. P20 isolated from the polluted environment is capable of degrading biphenyl and 4-chlorobiphenyl. The pcbABCD genes responsible for degradation of biphenyl and 4-chlorobiphenyl were cloned using pBluescript SK(+) from the chromosomal DNA of Pseudomonas sp. P20 to construct pCK1 and pCK102, harbouring pcbABCD and pcbCD, respectively. The 2, 3-DHBP dioxygenase gene, pcbC, was cloned again from pCK102 by using pKT230 which is known as a shuttle vector and pKK1 hybrid plasmid was constructed. The E. coli KK1 transformant obtained by transforming the pKK1 into E. coli XL1-Blue showed 2, 3-DHBP dioxygenase activity. The specific 2, 3-DHBP dioxygenase activity of E. coli KK1 was similar to that of the E. coli CK102, but much higher than those of the natural isolates, Pseudomonas sp. DJ-12 and Pseudomonas sp. P20.

• Proceedings of the IEEK Conference
• /
• 2001.06b
• /
• pp.257-260
• /
• 2001

Routing region modeling methods for PCB auto-routing system in Shape based type(non-grid method) used region process type and the shape located in memory as a individual element, and this element consumed small memory due to unique data size. In this paper we design PCB(Printed Circuit Board) auto-routing system using the auction algorithm method that 1) Could be reached by solving the shortest path from single original point to various destination, and 2) Shaped based type without any memory dissipation with the best speed. Also, the auto-routing system developed by Visual C++ in Window environment, and can be used in IBM Pentium computer or in various individual PC system.

• Journal of the Korean Society for Precision Engineering
• /
• v.20 no.8
• /
• pp.76-85
• /
• 2003

In this paper, a technical method for removing the solder from PCBs has been proposed to simplify the pulverizing process and to get higher quality of materials for recycling of the electronic parts in the Printed Circuit Boards (PCBs). There are several techniques to remove the solder from PCB, such as physical and chemical method, vibration, suction and blowing and so on. Among them, the suction technique turned out the best method by investigation. In the suction method, there are three variables for removing the solder. They are a temperature of the thermal wire, a velocity of moving PCB and a gap between PCB and thermal wire. To find the optimal variables for the system, an experiment has been conducted by a trial and error method. The optimal variables were found $220^{\circ}C$ of temperature, 11.58mm/s of velocity, 10mm of gap (A gap between suction hole and bottom of PCBs is 5mm). The result of the experiment shows that 50% of the solder were removed.

• Journal of the Microelectronics and Packaging Society
• /
• v.14 no.2 s.43
• /
• pp.41-47
• /
• 2007

Today lots of investigations on Embedded Passive Technology using materials and chip components have been carried out. We fabricated diplexers with 1005 sized-passives, which were made by burying chips in PCB substrate and surface mounting chip on PCB. 6 passive chips (inductors and capacitors) were used for the frequency divisions of $880\;MHz{\sim}960\;MHz(GSM)$ and $1.71\;GHz{\sim}1.88\;GHz(DCS)$. Two types of diplxer were characterized with Network analyzer. The chip buried diplexer showed extra 5db loss and a little deviation of 0.6GHz at aimed frequency areas, whereas the chip mounted diplexer showed man. 0.86dB loss within GSM field and max. 0.68dB within DCS field respectively. But few degradations were observed after $260^{\circ}C$ for 80min baking and $280^{\circ}C$ for 10sec solder floating.

• Resources Recycling
• /
• v.27 no.6
• /
• pp.23-29
• /
• 2018

Recently rapid economic growth and technological development have led to an increase in the generation of waste electrical and electronic equipment (WEEE). As the amount of electric and electronic waste generated increases, the importance of processing waste printed circuit boards (PCB) is also increasing. Various studies have been conducted to recycle various valuable metals contained in a waste PCB in an environmentally friendly and economical manner. To get anode slime containing Ag and Au, Anode copper prepared from PCB scraps was used by means of electro-refining. Ag and Au recovery was conducted by leaching, direct reduction, and ion exchange method. In the case of silver, the anode slime was leached at 3 M $HNO_3$, 100 g/L, $70^{\circ}C$, and Ag was recovered by precipitation, alkali dissolution, and reduction method. In the case of gold, the nitrate leaching residues of the anode slime was leached at 25% aqua regia, 200 g/L, $70^{\circ}C$, and Au was recovered by pH adjustment, ion exchange resin adsorption, desorption and reduction method. The purity of the obtained Au and Ag were confirmed to be 99.99%.

• Journal of Environmental Science International
• /
• v.14 no.5
• /
• pp.513-520
• /
• 2005

For the destruction of toxic chlorinated organic compounds, this study proposes improved supercritical water oxidation method (multistep oxidation) using sodium nitrate as an oxidizer. This method solves the problems involved in the existing supercritical water oxidation method. Multistep oxidation means that $NaNO_3$ is oxidized to $N_2\;via\;NaNO_2$ and NO. Toxic and hard to destroy organic substances like para-dichlorobenzen(4-DCBz), polychlorinate biphenyl(PCB) ware oxidized to non toxic substances in a condition, in which rapid pressure and temperature rise is restrained as much as possible. 4-dichlorobenzene(4-DCBz) and Polychlorinate biphenyl(PCB) in condition$(450^{\circ}C,\;p_w=0.25g/cm^3,\;30min)$ Was discomposed perfectly.

• Journal of Welding and Joining
• /
• v.33 no.3
• /
• pp.47-53
• /
• 2015

By the trends of electronic package to be more integrative, the fine Cu trace pitch of organic PCB is required to be a robust design. In this study, the short circuit failure mechanism of PCB with a Cl element under the Temperature humidity bias test ($85^{\circ}C$/85%RH/3.5V) was examined by micro-structural study. A focused ion beam (FIB) and an electron probe micro analysis (EPMA) were used to polish the cross sections to reveal details of the microstructure of the failure mode. It is found that $CuCl_x$ were formed and grown on Cu trace during the $170^{\circ}C$/3hrs and that $CuCl_x$ was decomposed into Cu dendrite and $Cl_2$ gas during the $85^{\circ}C$/85%RH/3.5V. It is suggested that Cu dendrites formed on Cu trace lead to a short circuit failure between a pair of Cu traces.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.17 no.12
• /
• pp.1169-1176
• /
• 2005

In this paper, thermal reliability of a closed type BLDC (Brushless DC) motor for high speed axial fan was analyzed by the accelerated life test. The closed type BLDC (Model No. MB1-8855-J01) motor was controlled by PCB module, which was composed of various electrical components. The failure of the closed type BLDC motor happened in PCB module due to high temperature. Failure mechanism of the closed type BLDC motor appears to be electrolyte dry out of capacitor. The accelerate life test was performed in temperature stress of $85^{\circ}C\;and\;105^{\circ}C$, respectively The failure data from the accelerated life test were analyzed and the life in each stress level was estimated with 960h and 261 h. At last, both life expression according to operating temperature of PCB module and life of the closed type BLBC motor in normal condition $(50^{\circ}C)$ were suggested.

• Proceedings of the KIPE Conference
• /
• 2020.08a
• /
• pp.205-208
• /
• 2020

This paper examines the approach, enabled by using SiC power devices, to unify the inverter design for central air conditioning (CAC) system for both single- and 3-phase input, and reduce the PFC inductor size to be PCB-mountable. By using SiC-instead of Si-diode in PFC stage, it is possible to increase the switching frequency from 16kHz to 60kHz to reduce the required PFC inductance from 0.93mH to 0.25mH, thus enable PCB-mounting of inductor. With the next step of using 1200V SiC MOSFET instead of Si-IGBT, the DC link voltage can be boosted from 311Vdc to 550Vdc in PFC stage, allowing the inverter and compressor used in 3-phase input CAC be used for single-phase input as well. Furthermore, using SiC MOSFET in inverter stage can further reduce total loss system total loss to 200.8 W. Simulation and experimental results are presented in the paper.