• Proceedings of the Korea Society for Simulation Conference
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• 1998.10a
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• pp.209-212
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• 1998

Tandem AGV 시스템은 기존의 AGV 시스템의 운영 문제를 쉽게 해결하기 위해 새롭게 제시된 개념의 시스템이다. 이와 같은 Tandem AGV 시스템의 성능은 설계적, 운영적 영향을 받게 된다. 본 연구에서는 Tandem AGV 시스템의 설계적 요소 중 한 부분인 Transfer Station의 위치를 결정하기 위한 알고리즘을 제시하였다. 그리고 시뮬레이션을 통해 그 성능을 평가하였다.

• Ceramist
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• v.22 no.2
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• pp.146-169
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• 2019

To overcome the theoretical efficiency of single-junction solar cells (> 30 %), tandem solar cells (or multi-junction solar cells) is considered as a strong nominee because of their excellent light utilization. Organic-inorganic halide perovskite has been regarded as a promising candidate material for next-generation tandem solar cell due to not only their excellent optoelectronic properties but also their bandgap-tune-ability and low-temperature process-possibility. As a result, they have been adopted either as a wide-bandgap top cell combined with narrow-bandgap silicon or CuIn_xGa_(1-x)Se₂ bottom cells or for all-perovskite tandem solar cells using narrow- and wide-bandgap perovskites. To successfully transition perovskite materials from for single junction to tandem, substantial efforts need to focus on fabricating the high quality wide- and narrow-bandgap perovskite materials and semi-transparent electrode/recombination layer. In this paper, we present an overview of the current research and our outlook regarding perovskite-based tandem solar technology. Several key challenges discussed are: 1) a wide-bandgap perovskite for top-cell in multi-junction tandem solar cells; 2) a narrow-bandgap perovskite for bottom-cell in all-perovskite tandem solar cells, and 3) suitable semi-transparent conducting layer for efficient electrode or recombination layer in tandem solar cells.

• Journal of the Korean Society of Physical Medicine
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• v.3 no.3
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• pp.169-176
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• 2008

Purpose : Tandem stance is a clinical measure of standing balance considered to assess postural steadiness in a heel-to-toe position by a temporal measurement. The aim of this study is to investigate postural steadiness and to explore the weight distribution between legs during 25s of quiet stance and tandem stance(right foot was leading) in healthy young adults. Methods : 107 healthy young adults(mean age 21.1 years) are participated. Weight distribution beneath both feet and sway distance were recorded while the subjects performed 25s of quiet stance and tandem stance. Results : Subjects placed more weight on the rear leg in tandem stance and on the left foot in quiet stance. So, quiet stance and tandem stance is not a task for equal weight bearing. Subjects show larger sway distance in anteroposterior direction of tandem stance than quiet stance. Conclusion : The results of this study will be useful to researchers and clinicians using tandem stance measures to evaluate postural steadiness and to predict fall. The results suggest that tandem stance is useful to treat of weight distribution and to improve of balace in elderly adults and stroke patients.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.5
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• pp.605-611
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• 2011

In this study, based on previous studies, the thrust generated by using flapping tandem wings is examined. We studied on the relationship between the parameters for characterizing oscillatory tandem wings (namely, the Strouhal number and Reynolds number) for thrust generation in micro flow regime. At each Reynolds number, Strouhal number, heaving amplitude, distance between tandem wings, and phase difference are varied and the flapping motions of tandem mode are calculated to find the optimum conditions for generating thrust. As a result, comparing with a single flapping mode, we found that the minimum Strouhal number for generating thrust is shifted down up to approximately 25% when the tandem flapping mode is applied.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.410.2-410.2
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• 2016

Tandem structure is promising in organic solar cells because of its double open-circuit voltage (VOC) and efficient photon energy conversion. In a typical tandem device, the two single sub-cells are stacked and connected by an interconnecting layer. The fabrication of two sub-cells are usually carried out in a glovebox filled with nitrogen or argon gas, which makes it expensive and laborious. We report a glovebox-free fabricated inverted tandem organic solar cells wherein the tandem structure comprises sandwiched interconnecting layer based on p-doped hole-transporting, metal, and electron-transporting materials. Complete fabrication process of the tandem device was performed outside the glove box. The tandem solar cells based on poly(3-hexylthiophene) (P3HT) and (6,6)-phenyl C61-butyric acid methyl ester (PCBM) can realize a high VOC, which sums up of the two sub-cells. The tandem device structure was ITO/ZnO/P3HT:PCBM/PEDOT:PSS/MoO3/Au/Al/ZnO-d/P3HT:PCBM/PEDOT:PSS/Ag. The separate sub-cells were morphologically and thermally stable up to 160 oC. The high stability of the active layer benefits in the fabrication processes of tandem device. The performance of tandem organic solar cells comes from the sub-cells with an 50 nm thick active layer of P3HT:PCBM, achieving an average power conversion efficiency (PCE) of 2.9% (n=12) with short-circuit current density (JSC) = 4.26 mA/cm2, VOC = 1.10 V, and fill factor (FF) = 0.62. Based on these findings, we propose a new method to improve the performance and stability of tandem organic solar cells.

• Journal of the Korean institute of surface engineering
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• v.48 no.3
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• pp.105-109
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• 2015

We studied emission characteristics of blue fluorescent multi-tandem OLEDs using $Al/MoO_x$ as charge generation layer(CGL). Threshold voltage for 2, 3, 4, and 5 units tandem OLEDs was 8, 11, 14 and 18 V, respectively. The threshold voltage in multi-tandem OLEDs was lower than multiple of 4 V for the single OLED. Maximum current efficiency and maximum quantum efficiency of single OLED were 7.6 cd/A and 5.5%. Maximum current efficiency for 2, 3, 4, and 5 units tandem OLEDs was 22.6, 31.4, 41.2, and 46.6 cd/A, respectively. Maximum quantum efficiency for 2, 3, 4, and 5 units tandem OLEDs was 11.8, 15.8, 21.8, and 25.6%, respectively. The maximum current efficiency and maximum quantum efficiency in multi-tandem OLEDs were higher than multiple of those for the single OLED. The intensity for 508 nm peak was changed and the peak wavelength was red shift by increase of tandem unit in electroluminescent emission spectra. These phenomena can be caused by micro-cavity effect with increasing of organic layer thickness.

• IE interfaces
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• v.15 no.1
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• pp.1-9
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• 2002

Tandem AGV system is obtained by partitioning all workstations into multiple zones assigning a single vehicle to each zone. In this paper, we propose an analytical model to design a tandem AGV system with multi-load AGVs. Using simulation, the performance of the proposed model is shown by comparing a conventional multi-load AGV system.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2000.04a
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• pp.509-512
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• 2000

AGV 는 자동화된 생산 시스템에 없어서는 안 되는 중요한 요소로 자리잡았다. 하지만 생산 시스템의 규모가 커짐에 따라 설계와 운영에 있어 많은 어려움이 생겼고, 이를 극복하기 위해서 새로운 형태의 AGV시스템이 제시되고 있다. 이중 대표적인 것이 Tandem AGV 시스템이다. Tandem AGV 시스템은 전체 시스템을 몇 개의 지역으로 분할하고, 하나의 지역에 한대의 차량을 할당하는 방식으로 운영의 효율성을 꾀하고 있다. 본 연구에서는 Multi-load AGV 를 사용하는 Tandem AGV 시스템을 설계하기 위한 효율적인 방법론을 제시하고자 한다.

• 한국데이터정보과학회:학술대회논문집
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• 2003.10a
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• pp.155-162
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• 2003

A tandem network in which all nodes have the same load is considered. We derive bounds on the probability that the total population of the tandem network exceeds a large value by using its relation to the stationary distribution. These bounds imply a stronger asymptotic limit than that in the large deviation theory.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.1015-1018
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• 2008

Tandem organic light-emitting diodes (OLEDs) do not always improve power efficiency over their conventional OLED counterparts. When a tandem OLED utilizes optimized EL units, increased power efficiency can only be achieved if the intermediate connector in the device has excellent charge injection capability.