• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.275-276
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• 2009

We have studied physical properties of organic light-emitting diodes (OLEDs) in a device with 7,7,8,8-tetracyanoquinodimethane (TCNQ). Since the TCNQ has a high electron affinity, it is widely used for a charge-transport and injection layer. And the TCNQ-derivatives have also been used to control the conductivity of the materials. It is known that a charge injection and transport in OLEDs with a TCNQ-derivative enhances a performance of the devices such as operating voltage and efficiency. To see how the TCNQ affects on the device performance, we have made a reference device in a structure of ITO(170nm)/TPD(40nm)/$Alq_3$(60nm)/LiF(0.5nm)/Al(100nm). And several type of devices were manufactured by doping TCNQ either in TPD or $Alq_3$ layer. The TCNQ layer was also formed in between the organic layers. N,N'-diphenyl-N,N'-di(m-tolyl)-benzidine (TPD), tri(8-hydroxy quinoline) aluminium ($Alq_3$), and TCNQ layers were formed by thermal evaporation at a pressure of $10^{-6}$ torr. The deposition rate was $1.0{\sim}1.5\;{\AA}/s$ for TPD, and $1.0{\sim}1.5\;{\AA}$ for $Alq_3$. The LiF was thermally evaporated at a deposition rate of $0.2\;{\AA}/s$ successively. The device with TCNQ-derivative improved the turn-on voltage compared to the one without TCNQ-derivative.

• Economic and Environmental Geology
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• v.39 no.6 s.181
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• pp.753-770
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• 2006

In urban areas, groundwater pollution is heavily affected by urbanization with land use types. This study aims to characterize groundwater quality and contamination in Sasang industrial area of Busan Metropolitan City where metalworking, machinery and footwear factories are located. Busan Metropolitan City is the highest in the utilization of groundwater resources among the metropolitan cities in Korea. $K^+,\;Na^+,\;Ca^{2+},\;Mg^{2+},\;Cl^-,\;SO_4^{2-}\;and\;HCO_3^-$ concentrations, and electrical conductivity (EC), total dissolved solids (TDS) and salinity are high in the areas near the Nakdong River. The results are attributed to the influence of salt water which intruded into the coastal sediments during sedimentation. In addition, the dominant chemical type of Ca-Cl indicates the influence of salt water in the geological formations as well as anthropogenic pollution. $SiO_2$ ion is interpreted to originate from both water-silicate mineral reactions and the decomposition of cement concretes. Trichloroethylene (TCE) was detected at 12 sites of total 18 sites. However, tetrachloroethylene (PCE) was detected at f sites and 1.1.1-trichloroethane (TCA) at 3 sites. According to the factor analysis, factor 1 was explained by 49.8%, factor 2 19.8%, and factor 3 11.0% with total 80.6% explanation. pH, TDS, salinity, $Ca^{2+},\;K^+,\;Mg^{2+},\;Na^+,\;Al^{3+},\;As^{3+},\;Cl^-\;and\;Fe^{2+}$ were positively highly loaded to factor 1. The chemical components loaded to factor 1 represent the chemical characteristics of both industrial pollution and influence by salt water. Based on the cluster analysis and distribution pattern of chemical components, the concentration of $Na^+,\;Ca^{2+},\;Cl^-,\;SO_4^{2-}\;K^+,\;and\;Mg^{2+}$ is high in the riverside area of the Nakdong River composed of coastal sediments that is influenced by salt water. The downstream area of the Hakjang Stream is judged to be affected by both salt water and artificial pollution. The other part of the study area is interpreted by anthropogenic pollution.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.168-169
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• 2009

본 연구에서는 ITO 표면 개질에 의한 유기 발광 소자의 특성 변화에 대해서 연구하였다. ITO 전극은 발광 소자의 투명 전극으로 널리 사용되고 있으며 이러한 발광 소자의 특성은 ITO의 표면 상태에 따라 민감하게 반응한다. ITO 표면 개질은 ITO와 유기물 사이의 쇼트기 장벽을 감소시키며, 전극과 유기물의 점착을 향상시켜 준다. 본 실험에서는 습식 처리 방식으로 self-assembled monolayer(SAM)을 사용하였다. 유기 발광 소자의 특성은 SAM 처리에 의해 향상 되었다. 유기 발광 소자는 ITO/SAM/TPD(50nm)/$Alq_3$(70nm)/LiF(0.5nm)/Al(100nm)의 구조로 제작하였으며, ITO의 표면 특성은 일반적인 특성 기술에 의해 연구되었다. SAM 처리된 소자는 SAM 처리하지 않은 소자에 비해 구동 전압, 발광 세기, 외부 양자 효율 등이 향상되었다. ITO의 SAM 처리 시간을 0/10/15/20/25분으로 하여 소자를 제작하였다. 15분간 SAM 처리한 소자는 SAM 처리하지 않은 소자에 비해 외부 양자 효율과 전류 효율이 2.6배 상승하였다. 본 실험을 통하여 ITO 표면 위에 SAM층을 삽입한 걸과, 구동 전압, 발광 세기, 효율 등이 향상됨을 알 수 있었다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.6
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• pp.451-456
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• 2013

To study emission properties of white phosphorescent organic light emitting devices (PHOLEDs), we fabricated white PHOLEDs of ITO(150 nm) / NPB(30 nm) / TcTa(10 nm) / mCP(7.5 nm) / light-emitting layer(25 nm) / UGH3(5 nm) / Bphen(50 nm) / LiF(0.5 nm) / Al(200 nm) structure. The total thickness of light-emitting layer with co-doping and blue-doping/co-doping using a host-dopant system was 25 nm and the dopant of blue and red was FIrpic and $Bt_2Ir$(acac) in UGH3 as host, respectively. The OLED characteristics were changed with position and thickness of blue doping layer and co-doping layer as light-emitting layer and the best performance seemed in structure of blue-doping(5 nm)/co-doping(20 nm) layer. The white PHOLEDs showed the maximum current density of $34.5mA/cm^2$, maximum brightness of $5,731cd/m^2$, maximum current efficiency of 34.8 cd/A, maximum power efficiency of 21.6 lm/W, maximum quantum efficiency of 15.6%, and a Commission International de L'Eclairage (CIE) coordinate of (0.367, 0.436) at $1,000cd/m^2$.

• Membrane Journal
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• v.18 no.3
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• pp.241-249
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• 2008

This study is to concentrate vanadium in Jeju groundwater using reverse osmosis processes, and to utilize the concentrate for vanadium water. Groundwater samples were taken from Wahyul, Ayum, and Seogwipo groundwater wells with different in vanadium content each other. Their vanadiuln concentrations were 31.8, 44.5, and 53.0 ppb, respectively. The rejection coefficients of every component in groundwater were increased with the increase of TMP At the TMP of $8 kg_f/cm^2$, the rejection coefficients of vanadium, sodium, potassium, aluminium, iron, and barium were $97.4%{\sim}99.0%,\;97.7%{\sim}97.8%,\;98.0%{\sim}98.3%,\;94.8%{\sim}97.5%,\;88.0%{\sim}96.4.0%$, and $97.9{\sim}98.0%$, respectively. And those of magnesium, calcium, chromium, mauganese, and strontium in three groundwater were more than 99.0% at the same TMP. It was possible that vanadium contents of Wahyul, Ayum and Seogwipo groundwater were concentrated into 58.6, 118.9, and 165.1 ppb, respectively, by 6 stages treatment at the recovery ratio of 15%. And these concentrated water (vanadium water) did not exceed the permissible drinking water standards.

• The Journal of the Petrological Society of Korea
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• v.6 no.3
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• pp.166-184
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• 1997

The Wondong caldea is a deeply eroded structure that offers spectacular exposures through the core and margins of a resurgent caldera. The Wondong Tuff and the postcollapse intrusions range from medium-silica rhyolite to rhyodacite in composition and the postcollapse lava and tuff, preresurgent and resurgent intrusions also range from medium-silica rhyolite to an-desite, which jump to gap dacite composition. The continuous compositional zonations generally define a large stratified magma system in the postcollapse and resurgent magma chamber. Isotopic and trace element evidence suggest that the compositional zonations might have resulted from the differentiations from crystal fractionations of a parental andesitic magma, accompanying a little contamination from the crustal assimilations near the chamber roof and wall. But chemically and isotopically distinct late intusions might have resulted from emplacement of any different magma batch.

• Asian-Australasian Journal of Animal Sciences
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• v.13 no.2
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• pp.149-154
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• 2000

The objectives of this study of Hanwoo (Korean Cattle) were 1) to estimate genetic parameters for direct and maternal genetic effects for birth weight, weaning weight, and six months weight which can be used for genetic evaluations and 2) to compare models with and without grandmatemal effects. Data were obtained from the National Livestock Research Institute in Rural Development Administration (RDA) of Korea and were used to estimate genetic parameters for birth weight (BW, n=10,889), weaning weight at 120-d (WW, n=8,637), and six month weight (W6, n=8,478) in Hanwoo. Total number of animals in pedigrees was 14,949. A single-trait animal model was initially used to obtain starting values for multiple-trait animal models. Estimates of genetic parameters were obtained with MTDFREML using animal models and derivative-free REML (Boldman et al., 1995). Estimates of direct heritability for BW, WW, and W6 analyzed as single-traits were 0.09, 0.03, and 0.02 from Model 3 which included direct and maternal genetic, maternal permanental environmental effects, and effects due to sire ${\times}$ region ${\times}$ year-season interaction, respectively. Ignoring sire ${\times}$ region ${\times}$ year-season interaction effect in the model (Model 2) resulted in larger estimates for direct heritability than for Model 3. Estimates of maternal heritability for BW, WW and W6 were 0.04, 0.05, and 0.07 from Model 3, respectively. The estimates of direct-maternal genetic correlation were positive for BW, WW, and W6 with Model 3 but were negative with Model 2 for WW and W6. Estimates of direct genetic correlations between BW and WW, BW and W6, and WW and W6 were large: 0.52, 0.45, and 0.90, respectively. Genetic correlations were also large and positive for maternal effects for BW with maternal effects for WW and W6 (0.69 and 0.74), and even larger for WW with W6 (0.97). The log likelihood values were the same for models including grandmatemal effects as for models including maternal effects for all traits. These results indicate that grandmatemal effects are not important for these traits for Hanwoo or that the data structure was not adequate for estimating parameters for a grandmatemal model.

• Journal of Electrical Engineering and Technology
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• v.13 no.4
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• pp.1638-1643
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• 2018

Multi-layer ceramic capacitors as decoupling capacitor were fabricated by dielectric composition with a high dielectric constant. The fabricated decoupling capacitors were embedded in the PCB of the 10G RF transceiver module and evaluated for the characteristics of electrical noise by the level of AC input voltage. In order to further improve the electrical properties of the $BaTiO_3$ based composite, glass frit, MgO, $Y_2O_3$, $Mn_3O$, $V_2O_5$, $BaCO_3$, $SiO_2$, and $Al_2O_3$ were used as additives. The electrical properties of the composites were determined by various amounts of additives and optimum sintering temperature. As a result of the optimized composite, it was possible to obtain a density of $5.77g/cm^3$, a dielectric constant of 1994, and an insulation resistance of $2.91{\times}10^{12}{\Omega}$ at an additive content of 5wt% and a sintering temperature of $1250^{\circ}C$. After forming a $2.5{\mu}m$ green sheet using the doctor blade method, a total of 77 layers were laminated and sintered at $1180^{\circ}C$. A decoupling capacitor with a size of $0.6mm(W){\times}0.3mm(L){\times}0.3mm(T)$ (width, length and thickness, respectively) and a capacitance of 100 nF was embedded using a PCB process for the 10G RF Transceiver modules. In the range of AC input voltage 400mmV @ 500kHz to 2200mV @ 900kHz, the embedded 10G RF Transceiver modules evaluated that it has better electrical performance than the non-embedded modules.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.314-315
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• 2008

We have studied a property change of organic light-emitting diodes (OLED)s due to a surface reformation of indium-tin-oxide(ITO) substrate. An ITO is widely used as a transparent electrode in light-emitting diodes, and the OLEDs device performance is sensitive to the surface properties of the ITO. The ITO surface reformation could reduce the Schottky barrier at the ITO/organic interface and increase the adhesion of the organic layer onto the electrode. We have studied the characteristics of OLEDs with a treatment by a wet processing of the ITO substrate. The self-assembled monolayer(SAM) was used for wet processing. The characteristics of OLEDs were improved by SAM treatment of an ITO in this work. The OLEDs with a structure of ITO/TPD(50nm)/$Alq_3$(70nm)/LiF(0.5nm)/Al(100nm) were fabricated, and the surface properties of ITO were investigated by using seneral characterization techniques. Self-assembled monolayer introduced at the anode/organic interface gave an improvement in turn-on voltage, luminance and external quantum efficiency compared to the device without the SAM layer. SAM-treatment time of the ITO substrate was made to be 0/10/15/20/25min. The current efficiency of the device with 15min. treated SAM layer was increased by 3 times and the external quantum efficiency by 2.6 times.

• Proceedings of the Mineralogical Society of Korea Conference
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• 2001.06a
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• pp.58-59
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• 2001

부산에서 북동쪽으로 대략 25km 떨어진 지점에 위치하고 있는 일광광산 부근의 지질은 백악기 화산암ㆍ퇴적암 그리고 이를 관입한 화강암류와 이 암주 내에 발달하는 구리-중석을 함유하고 있는 각력파이프광상으로 이루어져 있다. 일광광산의 화강암류는 거의 타원형으로 felsic한 중앙부와 mafic한 양상의 주변부로 나뉘어지며, 암주 내에 수직적인 원통형의 각력파이프가 광화대를 이루고 있고, 그 주변에는 모암변질대가 발달되어 있다. 각력파이프를 충진하고 있는 vein과 화강암의 중앙부에는 전기석이 풍부하게 산출되고 있다. 일광광산에서 산출되는 전기석은 야외 관찰시 각력파이프 중심에서부터 외곽부쪽으로 전기석의 풍부함이 감소하며 산출형태도 달라진다. 파이프에서 대략반경 150m내에서 전기석은 침상형 의 방사상 모양 내지 rosettes형으로 풍부하게 산출되며, 화강암내의 mafic한 암편을 치환한 형태로 산출되기도 한다. 암주의 중앙부 주변부에서는 거의 미세한 구상형으로 산재되어 나타나고 있다. 전기석은 복잡한 화학식 {(Na, Ca)(Fe, Mg)$_3$(Al, Li)$_{6}$(BO$_3$)$_3$Si$_{6}$O$_{18}$ (OH, F)$_4$}을 갖는 붕산 규산염광물이다. 이러 한 다양한 성분은 마그마의 진화과정, 모암의 특성, 온도, 압력, 성분과 같은 물리ㆍ화학적 성질에 따라 전기석의 성분이 체계적으로 변하기 때문에 모암과 전기석 기원과의 상관관계를 파악할 수 있다. 파이프 부근의 화강암류는 현미 경상에서 전기석이 석류석과 같이 풍부하게 나타나며 장석들은 변질받은 상태로 세리사이트, 녹렴석으로 나타나고, 흑운모와 각섬석은 녹니석화되어 변질된 상태를 보이고 있다. 파이프 중심에서 외곽부로 갈수록 전기석의 함량은 줄어들고 있고 장석들이 알바이트ㆍ칼스베드 쌍정을 보이며, 흑운모가 각섬석보다는 우세하게 나타나고 있다. 전기석은 주상 결정, 자형 내지 반자형의 입자로 다색성을 보이며, 결정 중심에서 가장자리로 갈수록 파란색과 황갈색의 광학적 누대구조를 관찰할 수 있다. 일광광산에서 산출되는 전기석에 대한 현미경 관찰은 열수기원임을 지시하고 있다. 야외조사와 현미경 관찰의 예비조사에 의하면 일광광산의 전기석이 형성된 환경은 다른2가지 화학적인 저장소의 혼합 효과의 결과로 생성되어진 것으로 예상된다. 일광의 화강암류를 만든 마그마는 전기석을 형성할 만큼의 Fe-Mg성분이 충분하지 않았을 것이다. 화강암 내에 흑운모와 각섬석의 결정작용에 의해 마그마의 Fe-Mg성분이 고갈되어지고 이로 인해 그 함량이 감소하며 상대적으로 마그마 내에 남은 붕소(B$_2$O$_3$)는 열수로 용리되고 흑운모, 각섬석과 평형을 유지하며 열수에 남아있게 된다. 잔류용융체에 남은 붕소의 함량은 전기석을 만들기에 충분함에도 불구하고, Fe-Mg 함량이 부족하여 마그마 기원의 전기석 결정을 만들 수가 없다가 광맥이 형성된 시기에 또 다른 열수가 공급되면서 이전의 평형이 깨지고 기존의 흑운모와 같은 염기성 광물이 붕소(B)를 함유한 새로운 열수와 반응하여 전기석을 형성한 것으로 예상한다. 앞으로 전암과 광물에 대해 지화학적 연구를 통해 화강암류와 전기석과의 지화학적 연관성, 주성분 원소와 열수의 특성과의 상관관계, 전기석의 기원(마그마 기원인지 열수기원인지)이 보다 정확하게 파악될 것이다. 마그마 진화에 따른 전기석의 성분변화와 기원을 이용하여 일광광산의 동광화대를 형성한 마그마 계에서 열수계로 이어지는 지질학적 과정을 이해할 수 있을 것이며, 암석 성인론적 지시자로서 어떠한 중요성을 갖는지 논의되어질 수 있다.