• Journal of the Korean Society of Industry Convergence
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• v.4 no.3
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• pp.289-294
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• 2001

In this paper a POCSAG receiver interface circuit for wireless remote control using pager system is presented. SM8212A and AT89C51 chips are used for the core of system design. The proposed system is able to communicate with computers through RS-232C interface, which enables users to manage the data from the pager system on computers in real time. Analysis of SM8212A for Ole algorithm of CPU control program is described. The hardware is implemented on a PCB and the control program is made by C++ and assembly language. The performance of designed system is confirmed by experiments using the TESCOM equipments.

• Proceedings of the KIPE Conference
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• 2020.08a
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• pp.257-258
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• 2020

본 논문에서는 고효율·고전력밀도를 위하여 WBG소자를 적용한 3kW 전기자동차용 LDC를 제안한다. SiC소자에 250kHz의 스위칭 주파수를 적용하였으며, 65℃의 냉각수 온도를 기준으로 모든 소자가 110℃ 이하로 온도관리가 될 수 있도록 냉각기를 설계하였다. 또한 센터탭 구조와 전류 더블러 구조 플라나 변압기의 단면적 비교를 통해 전류 더블러 정류기가 토폴로지로 선정되었다. Low Profile을 위하여 통합형 커스터마이징 플라나 코어 및 PCB 레이어를 설계·제작하였고 3kW 1차시 작품으로부터 96.36%의 효율과 3.68kW/L의 전력밀도를 달성하였다.

• Biotechnology and Bioprocess Engineering:BBE
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• v.5 no.6
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• pp.449-455
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• 2000

Pseudomonas sp. strain DJ-12 is a bacterial isolate capable of degrading 4-chlorobiphenyl (4CBP) as a carbon and energy source. The catabolic degradation of 4CBP by the strain DJ-12 was studied along with the genetic organization of the genes responsible for the crucial steps of the catabolic degradation. The catabolic pathway was characterized as being conducted by consecutive reactions of the meta-cleavage of 4CBP, hydrolytic dechlorination of 4-chlorobenzoate (4CBA), hydroxylation of 4-hydroxybenzoate, and meta-cleavage of protocatechuate. The pcbC gene responsible for the meta-cleavage of 4CBP only showed a 30 to 40% homology in its deduced amino acid sequence compared to those of the corresponding genes from other strains. The amino acid sequence of 4CBA-CoA dechlorinase showed an 86% homology with that of Pseudomonas sp. CBS3, yet only a 50% homology with that of Arthrobacter spp. However, the fcb genes for the hydrolytic dechlorination of 4CBA in Pseudomonas sp. DJ-12 showed an uniquely different organization from those of CBS3 and other reported strains. Accordingly, these results indicate that strain DJ-12 can degrade 4CBA completely via meta-cleavage and hydrolytic dechlorination using enzymes that are uniquely different in their amino acid sequences from those of other bacterial strains with the same degradation activities.

• Journal of the Korean Chemical Society
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• v.56 no.6
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• pp.692-699
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• 2012

The aim of the present study is to explore the possibility of utilizing loess and fly ash as well as activated carbon for the adsorptive removal of PCBs in transformer oil. Here, we investigated the effect of various factors such as temperature (5, 25, 55), contact time (30 min-3 day) and adsorbent does (1, 2.5, 5, 10 g) in detail. It was found that PCBs adsorption rate from transformer oil by activated carbon is more favored than loess at the equilibrium time of 60 minutes. The equilibrium data for both activated carbon and loess is fitted well to the Freundlich isotherm model. The rate constant and activation energy of PCBs adsorption in transformer oil on each adsorbent was analyzed by fitting a kinetic model at 5, 25 and $55^{\circ}C$. From the thermodynamic parameters, the PCBs adsorption process for transformer oil/activated carbon and loess system is spontaneous and endothermic in nature.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.8
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• pp.725-732
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• 2013

Recently, various applications for LED lightings are growing continuously due to their better performances such as low power consumption, longer life time, operation speed, controllability, high quality color rendering, and sustainability. However, in developing the high-powered LEDs illumination system, heat-sink problem is one of the important obstacle. In this paper, a heat-sink design with multi-layered structure for high-powered LEDs is proposed, which is composed of metal core PCB, heat-pipes, heat-sink plates, and fans. And also, in this paper, a design for LED controls using DMX512 protocols through RS-485 communications is proposed, which is considered as de facto international standard in LEDs illumination control and is widely used in landscape lighting and stage lighting. In this paper, LED control and its application techniques are introduced and the method of wireless remote control for main controller is proposed.

• Journal of Welding and Joining
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• v.33 no.3
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• pp.19-24
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• 2015

Joint properties of electric control unit (ECU) module using Sn-Cu-(X)Al(Si) lead-free solder alloy were investigated for automotive electronics module. In this study, Sn-0.5Cu-0.01Al(Si) and Sn-0.5Cu-0.03Al(Si) (wt.%) lead-free alloys were fabricated as bar type by doped various weight percentages (0.01 and 0.03 wt.%) of Al(Si) alloy to Sn-0.5Cu. After fabrications of lead-free alloys, the ball-type solder alloys with a diameter of 450 um were made by rolling and punching. The melting temperatures of 0.01Al(Si) and 0.03Al(Si) were 230.2 and $230.8^{\circ}C$, respectively. To evaluation of properties of solder joint, test printed circuit board (PCB) finished with organic solderability perseveration (OSP) on Cu pad. The ball-type solders were attached to test PCB with flux and reflowed for formation of solder joint. The maximum temperature of reflow was $260^{\circ}C$ for 50s above melting temperature. And then, we measured spreadability and shear strength of two Al(Si) solder materials compared to Sn-0.7Cu solder material used in industry. And also, microstructures in solder and intermetallic compounds (IMCs) were observed. Moreover, thickness and grain size of $Cu_6Sn_5$ IMC were measured and then compared with Sn-0.7Cu. With increasing the amounts of Al(Si), the $Cu_6Sn_5$ thickness was decreased. These results show the addition of Al(Si) could suppress IMC growth and improve the reliability of solder joint.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.36C no.3
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• pp.26-34
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• 1999

A new silicon-based IC interconnect transmission line parameter extraction methodology is presented and experimentally examined. Unlike the PCB or MCM interconnects, a dominant energy propagation mode in the silicon-based IC interconnects is not quasi-TEM but slow wave mode(SWM). The transmission line parameters are extracted taking the silicon substrate effect (i.e., slow wave mode) into account. The capacitances are calculated considering silicon substrate surface as a ground. Whereas the inductances are calculated by using an effective dielectric constant. In order to verify the proposed method, test patterns were designed. Experimental data have agreement within 10%. Further, crosstalk noise simulation shows excellent agreements with the measurements which are performed with high-speed time domain measurement ( i.e., TDR/TDT measurements) for test pattern, while RC model or RLC model without silicon substrate effect show about 20~25% underestimation error.

• Analytical Science and Technology
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• v.13 no.6
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• pp.802-809
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• 2000

Concentrations of polychlorinated biphenyl congeners (PCBs) in samples collected from 43 kindss of water, 35 kinds of soil and 11 kinds of sediment in various place of Korea have been monitored using GC/MS/SIM analytical method. In our investigation, mean recoveries were $83.8{\pm}10.4%$ for water, $94.9{\pm}12.2%$ for soil and sediment samples and $80.2{\pm}8.7%$ for the spiked $^{13}C{_{12}}$-PCBs. Detection limits of PCBs for water, soil and sediment samples are 0.01 ng/ml and 0.05 ng/g. PCB congeners in water samples were not detected within quantitation limit, but trace amounts were detected in most of soil and sediment samples. The contamination level of PCBs in Korea was evaluated to be lower than in advanced countries like USA, Europe and Japan.

• Korean Journal of Materials Research
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• v.24 no.3
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• pp.166-173
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• 2014

The effects of printed circuit board electroless nickel immersion gold (ENIG) and organic solderability preservative (OSP) surface finishes on the electromigration reliability and shear strength of Sn-3.5Ag Pb-free solder bump were systematically investigated. In-situ annealing tests were performed in a scanning electron microscope chamber at 130, 150, and $170^{\circ}C$ in order to investigate the growth kinetics of intermetallic compound (IMC). Electromigration lifetime and failure modes were investigated at $150^{\circ}C$ and $1.5{\times}10^5A/cm^2$, while ball shear tests and failure mode analysis were conducted under the high-speed conditions from 10 mm/s to 3000 mm/s. The activation energy of ENIG and OSP surface finishes during annealing were evaluated as 0.84 eV and 0.94 eV, respectively. The solder bumps with ENIG surface finish showed longer electromigration lifetime than OSP surface finish. Shear strengths between ENIG and OSP were similar, and the shear energies decreased with increasing shear speed. Failure analysis showed that electrical and mechanical reliabilities were very closely related to the interfacial IMC stabilities.

• Analytical Science and Technology
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• v.22 no.6
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• pp.449-457
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• 2009

Total PCBs (62 congeners) has been determined in the retailed foods by the isotopic dilution method and the exposure assessment has been performed. Put into a food sample $^{13}C$-labeled standard for recovery was added and then it was extracted, cleaned-up by multi-layer column chromatography and then analyzed by HRGC/MS. The average levels (ng/g) detected was 0.1 for rice, 1.8~3.4 for meats, 0.3~3.7 for milk and dairy products, 10.0 for egg and 0.8~34.4 for fishes. Distribution of total PCBs was in order of fishes (94.4%) > meats (2.3%) > eggs (1.7%) > milk and dairy products (1.3%) > rice (0.3%). The estimated daily intake(EDI) was 14 ng/kg bw/day. It was concluded that there was no health risk at all.