• Journal of the Korean Society for Precision Engineering
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• v.15 no.8
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• pp.145-155
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• 1998

An $H{\infty}$ controller with a roll eccentricity filter is proposed to alleviate the effect of entry thickness variation and roll eccentricity occured in rolling stands themselves of tandem cold mills. A robust controller to the disturbances is designed by H$_{\infty}$ control techniques, which can reflect the input direction of disturbances and the knowledge of disturbance spectrum in the frequency domain. First, fundamental problems in tandem cold mills such as process transport delay inherent in the exit thickness measurement and the feedforward loading of roll eccentricity signals on the exit thickness be overcome by the roll eccentricity filtering and the compensation for the error of gaugemeter thickness estimator. And non-satndard $H{\infty}$ control problem caused by the selection of weighting function having poles on the $J{\omega}$-axis is discussed. The resultant controller composed by an $H{\infty}$ controller and an estimator for the roll eccentricity is evaluated through computer simulations. The effectiveness of the proposed control method is compared to that of the conventional LQ controller method and a feedforward controller for the roll eccentricity, which has been already studied.

• Journal of Information Display
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• v.8 no.2
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• pp.20-24
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• 2007

Efficient white organic light-emitting diodes are fabricated with the blue and red electroluminescent (EL) units electrically connected in a stacked tandem structure by using a transparent doped organic p/n junction. The blue and red EL units consist of the light-emitting layer of 1,4-bis(2,2-diphenyl vinyl)benzene (DPVBi) and 4-dicyanomethylene-2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[i,j] quinolizin-8-yl)vinyl]-4H-pyran) (DCM2) doped tris(8-hydroxyquinoline) aluminum $(Alq_3)$, respectively. The organic p-n junction consists of ${\alpha}-NPD$ doped with $FeCl_3$ (15 % by weight ratio) and $Alq_3$ doped with Li (10 %). The EL spectra exhibit two peaks at 448 and 606 nm, resulting in white light-emission with the Commission Internationale d'Eclairage (CIE) chromaticity coordinates of (0.36, 0.24). The tandem device shows the quantum efficiency of about 2.2 % at a luminance of 100 $cd/m^2$, higher than individual blue and red EL devices.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.1
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• pp.25-34
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• 2000

In this paper, we design a H^\infty servo controller for gauge control of tandem cold mill. To improve the performance of the AGC(Aotomatic Gauge Control) system based on the Taylor linearized model of tandem cold mill, the H^\infty servo controller is designed to satisfy robust stability, disturbance attenuation and robust tracking properties. The H^\infty servo controller problem is modified as an usual H^\infty control problem, and the solvability condition of the H^\infty servo problem depends on the solvability of the modified H^\infty control problem. Since this modified problem does not satisfied standard assumptions for the H^\infty control problem, it is solved by an LMI(Linear Matrix Inequality) technique. Consequently, the comparison between the H^\infty servo controller and the existing PID/FF(FeedForward) controller shows the usefulness of this study.

• Proceedings of the Korea Information Processing Society Conference
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• 2006.11a
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• pp.617-620
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• 2006

개방화시대에 제품의 국제경쟁력을 확보하기 위해서는 Unix나 Tandem 환경의 시스템운영관리 측면에서 실시간 모니터링 운영의 효율성이 증대 하고 있고 이를 바탕으로 서비스의 품질 및 기술력 향상과 고객만족 서비스 등 경제성이 필수적으로 요구되고 있다. 기존의 시스템관리 기능의 운영측면에서 보다는 보다 더 다양한 고객의 요구가 반영이 가능한 새로운 형태의 실시간 업무지원이 가능한 모니터링 시스템 개발이 필요한 시점이다. 기존의 시스템관리 기능에서 보다 업무지원이 기능이 강하된 모니터링 툴 이다. 즉 업무(Application) 프로세스의 장애현상에 따른 무응답을 사전 감시하고 System의 자원사용현황을 개발 및 운영자 위주의 실시간으로 감시환경 모니터링 서비스 제공이 가능한 기능으로 설계 따라서 시스템관리에서 보다 안정적인 운영을 제공 할 수 있다. 본 연구에서는 업무 프로세스의 장애를 점검할 수 있는 모니터링 툴 검토하여 실무자를 통하여 업무장애 유형에 따른 감시항목 및 의견 수렴, 요건정의에 따른 업무설명회 수행, 탠덤 시스템 모니터링 프로젝트 수행 필요한 기능을 개발 할 것이다. 또한 시스템 운영자 입장에서 실시간 모니터링 서비스를 통하여 업무(Application)프로그램의 전송지연 및 장애 원인을 한눈에 파악 점검 하도록 하며 각 기능별 시스템(System)별 장애 감시 통하여 사용자에서 현재 상태를 종합음성경보(SMS) 구축 연계하여 지원한다. 따라서, 본 논문에서는 중요한 요소로 기존의 많은 Unix나 Tandem 환경의 시스템관리 기능을 비교 분석을 통하여 보다 효율성이 높은 고객서비스 기능과 업무지원이 가능한 실시간 시스템관리 모니터링 툴을 개발 한다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2009.06a
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• pp.167-168
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• 2009

As the rapid increase of the container trade, most of the container terminals strive to improve the container handling productivity. Therefore, they consider to find efficient operating strategies and to introduce new container handling facilities. In terms of equipment, there are a variety of types of quay cranes. Single-lift crane operates only one container regardless of size and twin-lift crane operates two 20' containers or one 40' container simultaneously. Tandem crane, recently introduced, can operate four 20' containers or two 40' containers simultaneously. In this paper, we propose the mathematical model and the solution procedure of the ship loading scheduling problem for the tandem crane.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.310.1-310.1
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• 2013

We show the novel hot electron based-solar energy conversion using tandem structured Schottky diode with double Schottky barriers. In this report, we show the effect of the double Schottky barriers on solar cell performance by enhancing both of internal photoemission and band-to-band excitation. The tandem structured Au/Si diode capped with TiO2 layer as second semiconductor exhibited improved ability for light harvesting. The proposed mechanisms consist of multiple reflections of hot electrons and additional pathway of solar energy conversion due to presence of multiple interfaces between thin gold film and semiconductors. Short-circuit photocurrent measured on the tandem structured Au/Si diodes under illumination of AM1.5 increased by approximately 70% from 3.1% to 5.3% and overall incident photon to electron conversion efficiency (IPCE) was enhanced in visible light, revealing that the concept of the double Schottky barriers have significant potential as novel strategy for light harvesting.

• Food Science of Animal Resources
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• v.41 no.5
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• pp.816-825
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• 2021

This study aims to validate a fast method of simultaneous analysis of 365 LCamenable and 142 GC-amenable pesticides in hen eggs by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and gas chromatography-tandem mass spectrometry (GC-MS/MS), respectively, operating in multiple reaction monitoring (MRM) acquisition modes. The sample preparation was based on quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction. Key method performance parameters investigated were specificity, linearity, limit of quantification (LOQ), accuracy, precision and measurement uncertainty. The method was validated at two spiking levels (10 and 50 ㎍/kg), and good recoveries (70%-120%) and relative standard deviations (RSDs) (≤20) were achieved for 92.9% of LC-amenable and 86.6% of GC-amenable pesticide residues. The LOQs were ≤10 ㎍/kg for 94.2% of LC-amenable and 92.3% of GC-amenable pesticides. The validated method was further applied to 100 egg samples from caged hens, and none of the pesticides was quantified.

• Korean Journal of Materials Research
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• v.32 no.7
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• pp.320-325
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• 2022

Single OLED and tandem OLED was manufactured to analyze the electroluminescence characteristics of DC driving, AC driving, and full-wave rectification driving. The threshold voltage of OLED was the highest in DC driving, and the lowest in full-wave rectification driving due to an improvement of current injection characteristics. The luminance at a driving voltage lower than 10.5 V (8,534 cd/m²) of single OLED and 20 V (7,377 cd/m²) of a tandem OLED showed that the full-wave rectification drive is higher than that of DC drive. The luminous efficiency of OLED is higher in full-wave rectification driving than in DC driving at low voltage, but decrease at high voltage. The full-wave rectification power source may obtain higher current density, higher luminance, and higher current efficiency than the AC power source. In addition, it was confirmed that the characteristics of AC driving and full-wave rectification driving can be predicted from DC driving characteristics by comparing the measured values and calculated values of AC driving and full-wave rectification driving emission characteristics. From the above results, it can be seen that OLED lighting with improved electroluminescence characteristics compared to DC driving is possible using full-wave rectification driving and tandem OLED.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.2
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• pp.294-301
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• 2012

Shipbuilding industry has used a lot of $CO_2$ gas as a shielding gas for arc welding and thus, development of welding equipment which can reduce the amount of $CO_2$ gas is requested widely. Therefore, this study is focused on the examination of optimum welding torch distance of Tandem welding system as a fundamental study for the optimum shape design of torch nozzle. $CO_2$ shielding gas distribution and welding bead shape formation by the torch distance are examined. Results show that according to the torch distance variation, most effective shielding gas layer can be formed and quantitative determination of the optimum torch distance can result in the reduction of $CO_2$ shielding gas consumption.

• Clinical and Experimental Pediatrics
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• v.48 no.5
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• pp.561-564
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• 2005

Isolated deficiency of 3-methylcrotonyl CoA carboxylase is a rare disorder of the catabolic pathway for leucine and many patients have mild symptoms or no symptom. However, the introduction of tandem mass spectrometry in newborn screening has revealed an unexpectedly high incidence of this disorder. We report an asymptomatic premature infant with isolated 3-methylcrotonyl CoA carboxylase deficiency detected by newborn screening program using tandem mass spectrometry. She was born at preterm, 36 weeks of gestation and her birth weight was 1,912 gm. She was delivered by Cesarian section due to maternal preeclampsia and oligohydramnios. An elevation of 3-hydroxyisovalerylcarnitine in a blood sample obtained at Seven days was detected by tandem mass screening. Massively elevated excretion of 3-hydroxyisovalerate and 3-methylcrotonylglycine was detected in the urine collected at 15 days. L-carnitine(100 mg/kg/day) was administrated orally to correct sencondary carnitine deficiency. Carnitine is conjugated with metabolites, to decrease the potential toxic effects. She is asymptomatic to date, and her growth and development are within normal limits.