| 1. |
- Kim, Kyung Ho, 1984, et al.
(författare)
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Apparent Power Law Scaling of Variable Range Hopping Conduction in Carbonized Polymer Nanofibers
- 2016
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- We induce dramatic changes in the structure of conducting polymer nanofibers by carbonization at 800 degrees C and compare charge transport properties between carbonized and pristine nanofibers. Despite the profound structural differences, both types of systems display power law dependence of current with voltage and temperature, and all measurements can be scaled into a single universal curve. We analyze our experimental data in the framework of variable range hopping and argue that this mechanism can explain transport properties of pristine polymer nanofibers as well.
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| 2. |
- Park, D. -M, et al.
(författare)
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Comparative study on added resistance of a container ship in waves
- 2019
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Ingår i: Proceedings of the International Offshore and Polar Engineering Conference. - : International Society of Offshore and Polar Engineers. - 9781880653852 ; , s. 4418-4425
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Konferensbidrag (refereegranskat)abstract
- This paper presents a comparative study on the motion responses and added resistance of a container ship. Eight institutions participated in the comparative study, and ten numerical results were compared with two experimental results. Two experimental results were obtained from Seoul National University towing tank and Sweden SSPA seakeeping basin. The results of two experimental institutions in head sea condition were compared and showed good agreement with each other. The difference in motion responses and added resistance according to the numerical analysis method were compared. Even though the same program was used, it was observed that different results were obtained depending on the users. The comparison of the motion response and the added resistance according to the change of wave slope showed that the added resistance greatly changed according to the wave slope. This tendency was the same in experimental results and CFD analysis results. From the comparative study, the influence of the experiment method on the added resistance, and the characteristics of numerical each code were identified.
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| 3. |
- Álvarez-Asencio, Ruben, et al.
(författare)
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Molecular-scale shear response of the organic semiconductor β -DBDCS (100) surface
- 2017
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Ingår i: Physical Review B. - 2469-9950 .- 2469-9969. ; 96:11
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Tidskriftsartikel (refereegranskat)abstract
- In this work we present friction-force microscopy (FFM) lattice-resolved images acquired on the (100) facet of the semiconductor organic oligomer (2Z,2′Z)-3,3′-(1,4-phenylene)bis(2-(4-butoxyphenyl)acrylonitrile) (β-DBDCS) crystal in water at room temperature. Stick-slip contrast, lateral contact stiffness, and friction forces are found to depend strongly on the sliding direction due to the anisotropic packing of the molecular chains forming the crystal surface along the [010] and [001] directions. The anisotropy also causes the maximum value of the normal force applicable before wearing to increase by a factor of 3 when the scan is performed along the [001] direction on the (100) face. Altogether, our results contribute to achieving a better understanding of the molecular origin of friction anisotropy on soft crystalline surfaces, which has been often hypothesized but rarely investigated in the literature.
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| 4. |
- Park, D. -M, et al.
(författare)
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Experimental and numerical studies on added resistance of ship in oblique sea conditions
- 2019
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Ingår i: Ocean Engineering. - : Elsevier Ltd. - 0029-8018 .- 1873-5258. ; 186
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, the added resistance of a large tanker is estimated experimentally and numerically in oblique sea. Experiments on ship motion response and added resistance in oblique sea are performed in the SSPA seakeeping basin. The experiments are conducted using the self-propulsion test for seven wave directions between 180° and 0°. In the self-propulsion test, the added resistance is estimated from the difference between the thrust of the propeller in calm water and waves. In the case of the head sea, the results are compared with those obtained from the captive test at the towing test of Seoul National University. As numerical method, two methods are selected: the strip method and the 3D Rankine panel method. The maximum value of the added resistance is observed between the incident wave directions of 180° and 150°. From 120°, the added resistance tends to decrease and the peak of the added resistance shifted to the short waves. Through the two numerical analysis methods, the tendency of added resistance and the cause of the change of the added resistance in the oblique sea are investigated.
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| 5. |
- Park, M. S., et al.
(författare)
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InAs/GaAs p-i-p quantum dots-in-a-well infrared photodetectors operating beyond 200 K
- 2014
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Ingår i: Electronics Letters. - Stevenage, United Kingdom : Institution of Engineering and Technology (IET). - 1350-911X .- 0013-5194. ; 50:23, s. 1731-1732
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Tidskriftsartikel (refereegranskat)abstract
- High-temperature operating performance of p-i-p quantum dots-in-awell infrared photodetectors (QDIPs) is successfully demonstrated. The optically active region consists of 10 layers of p-doped selfassembled InAs quantum dots (QDs) asymmetrically positioned in In0.15Ga0.85As quantum wells (QWs). The dark current is suppressed by an incorporated superlattice (SL) structure composed of 10 pairs of AlGaAs/GaAs heterostructure. The very low recorded dark current makes the fabricated p-i-p QDIPs suitable for high-temperature operation. The measured photoresponse reveals broad mid-wave infrared (MWIR) detection up to 200 K.
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