• Journal of Magnetics
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• 제15권1호
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• pp.7-11
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• 2010

Spin-orbit coupling (SOC) is a source of strong spin dephasing in two- and three-dimensional semiconducting systems. We report that spin dephasing in a two-dimensional electron gas can be suppressed by introducing a quantum point contact. Surprisingly, this suppression was not limited to the vicinity of the contact but extended to the entire two-dimensional electron gas. This facilitates the electrical control of the spin degree of freedom in a two-dimensional electron gas through spin-orbit coupling.

• Transactions on Control, Automation and Systems Engineering
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• 제4권1호
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• pp.2-8
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• 2002

This paper discusses haptic display for grasping a virtual object by two fingers. Much research has been done on fundamental analysis for stability of haptic display. But it is difficult to apply the results immediately to grasping situations by two fingers, since the studies usually deal with a single device and a single object and the fingertip force in grasping situations has two components, internal and external components. The conventional methods, which specify the coupling impedance at each contact point separately, have no other alternative but to specify the impedance for the sum of the internal and external components. So even if only the impedance for the external force should be changed, the impedance for the internal force is also changed at the same time. In this paper, a new method, in which the coupling impedance is specified separately for the internal and external forces, is proposed and the stability of the proposed method is discussed using passivity analysis for 1 -DOF(Degree-Of-Freedom) system. Finally, some experiments are performed to study the effects of the proposed method.

• Fibers and Polymers
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• 제2권3호
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• pp.159-163
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• 2001

Five yellow disperse dyes were synthesized and their dyeing, fastness and photodegradation behaviors were investigated. It was found that dyes derived from phenylindole and N-alkylaminobenzene showed dye uptake directly proportional to the dye concentration, but the build-up of dyes derived from carbazole and pyridone were not good. The wavelength at maximum absorption. molar extinction coefficient. and the tendency to the photodegradation were strongly dependent on the electron donating ability of the coupling component. The dye, whose coupling component was phenylindole, possessed the excellent dyeing properties and the high degree of lightfastness. UVA had an effect on the inhibition of the photodegradation especially for the easily photodegradabte dyes.

• 한국염색가공학회지
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• 제33권4호
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• pp.317-326
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• 2021

In this study, we investigated for Bio-EPDM foam with oyster shell surface modified earth coupling agent. Experiments were carried out to confirm the bio-EPDM/Oyster shell foam applying content of earth coupling agent. The cure characterization were evaluated by measuring the mooney viscosity and oscillating disc rheometer (ODR). Mechanical properties such as hardness, tensile strength, elogation at break and tear strength were measured, and changes of mechanical properties were also evaluated after immersion in NaCl solution. In addition degree of volume change was measured after immersing the Bio-EPDM foam in NaCl solution and the low-temperature permanent compression set was evaluated at 4℃. To evaluate the low-temperature characteristics of Bio-EPDM/Oyster shell, the glass transition temperature was measured using Differential Scanning Calorimeter (DSC). As a result as the content of the earth coupling agent increased up to 3phr, the crosslinking density and mooney viscosity increased, and the mechanical properties and low-temperature permanent compression set improved, but from 4phr, it was rather decreased. The change in the glass transition temperature was insignificant, and the foam cell appeared to be uniform when the earth coupling agent was applied.

• Bulletin of the Korean Chemical Society
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• 제35권7호
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• pp.1979-1984
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• 2014

We have developed an efficient method to generate highly active Pd and PdO nanoparticles (NPs) dispersed on graphene and graphene oxide (GO) by an impregnation method combined with thermal treatments in $H_2$ and $O_2$ gas flows, respectively. The Pd NPs supported on graphene (Pd/G) and the PdO NPs supported on GO (PdO/GO) demonstrated excellent carbon-carbon cross-coupling reactions under a solvent-free, environmentally-friendly condition. The morphological and chemical structures of PdO/GO and Pd/G were fully characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). We found that the remarkable reactivity of the Pd/G and PdO/GO catalysts toward the cross-coupling reaction is attributed to the high degree of dispersion of the Pd and PdO NPs while the oxidative states of Pd and the oxygen functionalities of graphene oxide are not critical for their catalytic performance.

• 한국항해항만학회지
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• 제27권5호
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• pp.451-458
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• 2003

일반적으로 메타센터높이가 작은 선박이나 고속선의 경우에는 조종운동 시 큰 횡동요각을 유발하는 것으로 알려져 있다. 이러한 선박의 조종성능 예측 시에는 조종운동에 횡동요의 영향을 고려해야만 보다 정확한 결과를 얻을 수가 있다 즉, 조종운동을 다루는 전후동요, 좌우동요, 선수동요에 횡동요를 포함시키는 4자유도 운동방정식이 요구된다. 본 연구에서는 지금까지 여러 연구자들에 의해 제안되어 있는 4자유도 조종운동 수학모델을 검토 분석하고, 이들 실험자료를 재정리하여 보다 간결하고 실용적인 새로운 수학모델을 제안한다. 아울러 기존의 복잡한 수학모델과 새로운 수차모델에 의한 조종운동 시뮬레이션을 각각 수행하고 그 결과를 비교 검토하여 본 연구에서 제안한 수학모델의 유용성을 검증한다.

• Macromolecular Research
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• 제15권6호
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• pp.541-546
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• 2007

The combination of atom transfer radical polymerization (ATRP) and click chemistry was employed for the efficient preparation of well-defined block copolymers. Bromo terminated poly(methyl acrylate) (pMA-Br) was prepared by an ATRP initiator, ethyl-2-bromoisobutyrate (EBiB). Subsequently, the bromine chain end of pMA-Br was converted to an azide group by simple nucleophilic substitution reaction. ${\alpha}-Alkyn-{\omega}-bromo-functionalized$ polystyrene was also synthesized by ATRP using the alkyn-functionalized initiator, propargyl-2-bromoisobutyrate (PgBiB). In both cases, the conversion was limited to a low level to ensure a high degree of chain end functionality. Then the coupling reaction between the azide end group in $pMA-N_3$ and alkyn-functionalized PgBiB-pSt was performed by Cu(I)catalysis. This coupling reaction was monitored by gel permeation chromatography (GPC). The synthesized block copolymer was characterized by FT-IR, $^1H-NMR$ spectroscopy and $^1H-^1H$ COSY correlation spectroscopy.

• 대한의용생체공학회:의공학회지
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• 제40권1호
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• pp.15-19
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• 2019

In this study, Theta Gamma Coupling (TGC) analysis was carried out after performing simple and repeated upper limb exercise and comparative experiment to observe changes in the motor cortex of the brain through TGC and to see if mobile rehabilitation therapy is actually effective. As a result, exercise using mobile devices showed higher TGC values in motor cortex as compared with simple repeat upper limb exercise. In addition, paired t-test using SPSS showed statistically significant difference between exercise using mobile devices and simple repeat exercise at P3(t=3.390, df(degree of freedom)=12, p value=0.005). Exercise using mobile devices is effective for rehabilitation because it increases the Theta-Gamma Coupling and activates the motor cortex. Also, since the mobile game contents required the subject to detailed athletic ability adjustment with immersion in the task, it may be thought that brain activation is stronger than simple rehabilitation.

• 접착 및 계면
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• 제3권2호
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• pp.30-39
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• 2002

실리카로 보강된 천연고무 가황물에서 가황촉진제의 양이 열노화에 의한 가교밀도의 변화에 미치는 영향에 대해 연구하였다. 또한 실란커플링제의 영향도 조사하였다. 가황촉진제로는 N-tert-butyl-2-benzothiazole sulfenamide(TBBS)를 실란 커플링제로는 bis-(3-(triethoxysilyl)-propyl)-tetrasulfide(TESPT)를 사용하였다. 가황물을 열노화 시키면 가교밀도는 증가하였고 노화 온도가 높을수록 그 변화 정도는 컸다. 실란 커플링제가 포함되지 않은 가황물의 가교밀도 변화가 실란 커플링제를 포함한 것에 비해 더 크게 나타났다. 실란 커플링제가 포함되지 않은 가황물의 경우에는 가교밀도의 변화에 대한 활성화 에너지가 가황촉진제의 함량이 증가할수록 순차적으로 낮아지는 경향을 보였다.

• 호남수학학술지
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• 제39권4호
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• pp.617-635
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• 2017

By applying a classical approach for scalar rational interpolation problem, certain type of minimal interpolation problem for rational matrix functions is solved. It is shown that an appropriately defined matrix plays a key role in solving the minimal problem.