http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Phase-field Model for the Pinchoff of Liquid-liquid Jets
김창헌,신승호,이현근,김준석 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.55 No.4
Understanding pincho in a liquid-liquid jet is one of the fundamental problems in the physics of °uid. Pinchoff has a wide variety of applications, such as in ink-jet printers. We have need a phase-¯eld model to numerically investigate the breakup of a forced liquid jet into drops in immiscible liquid-liquid systems. In the phase-¯eld model, the classical sharp interface between the two immiscible °uids is represented by a transition region of small, but ¯nite, width. Across this width the composition of one of the two °uids changes continuously. The phase-¯eld method can deal with topological transitions, such as breakup and reconnection, smoothly without ad-hoc \cut and connect" or smoothing procedures. We found the numerical results for the pinchoff of liquid- liquid jets with surface tension to be in good agreement with experimental data. In particular, we investigated the axial velocities and the vorticity structures around the jet neck before and after pinchoff.
RECURSIONS FOR TRACES OF SINGULAR MODULI
김창헌 충청수학회 2008 충청수학회지 Vol.21 No.2
We will derive recursion formulas satisfied by the traces of singular moduli for the higher level modular function.
김창헌,김용남 대한물리치료학회 2018 대한물리치료학회지 Vol.30 No.3
Purpose: The purpose of this study was to investigate the effects of combined training using proprioceptive neuromuscular facilitation (PNF) patterns and treadmills on the balance and walking ability of stroke patients. Methods: Twenty-three stroke patients were randomized into a control group (n=11), receiving only treadmill training and an experimental group (n=12) receiving combined training. The use of both PNF exercise and treadmill were implemented in the combined training. Interventions were performed 5 times a week for 6 weeks. Balance ability was measured by a timed up and go (TUG) test. Walking ability was measured by a 10-meter walk test (10MWT) and a 6-minute walk test (6MWT). A paired t-test was used to compare differences between pre- and post-intervention and independent t-tests were used to compare between groups. Results: Changes in TUG, 10MWT, and 6MWT before and after interventions were significantly different for both the experimental group and the control group (p<0.05). In addition, within-group changes in the TUG, 10MWT, and 6MWT were more effective in the experimental group than in the control group (p<0.05). Conclusion: Combined training using PNF techniques and treadmills may be useful in improving the balance and walking ability of stroke patients.
빠른 경과의 진행성 죽상경화증과 뇌경색을 동반한 Takayasu 동맥염
김창헌 대한뇌졸중학회 2007 Journal of stroke Vol.9 No.2
Takayasu arteritis (TA) is a chronic inflammatory vascular disorder causing stenosis or obstruction of the aorta and its major branches. We experienced a 65-year-old patient with TA combined with rapidly progressive atherosclerosis and cerebral infarction despite the steroid and antiplatelet therapy for the vasculitis. In this case, multifactorial causes including renovascular hypertension, obesity, old age and inflammatory processes of vasculitis may have facilitated the progression of atherosclerosis, resulting in the cerebral infarction. (Korean J Stroke 2007;9:157-160)
김창헌,하도영,이영희,이동진,김한도 한국청정기술학회 2017 청정기술 Vol.25 No.4
To obtain epoxy resin with permanently attached flame-retardant groups, phosphorus compound containing di-hydroxyl group [10-(2,5-dihydroxyphenyl)-9,10-dihydro-9-oxa-10-phospha phenanthrene-10-oxide, DOPO-HQ] and silicone compound containing di-hydroxyl group (polydimethylsiloxane, hydroxyl terminated, PDMS) were reacted with uncured epoxy prepolymer (diglycidyl ether of bisphenol A, DGEBA) and then cured using 4,4-diaminodiphenylmethane (DDM) as a crosslinking agent. The properties of the resulting epoxy materials were characterized using Fourier transform infrared (FTIR) spectrometer, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), limiting oxygen index (LOI) test/vertical burning test (UL 94-V test), tensile properties test and impact test. This study examined the effect of phosphorus/silicone compound contents on the thermal/mechanical properties and flame retardancy of cured epoxy resins containing phosphorus and silicone compounds. It was found that the thermal/mechanical properties of epoxy resins containing phosphorus and silicone components were higher than those of simple epoxy resin. The flame-retardancy (LOI: 29.9 ~ 31.8% and UL 94-V: V-0) of all samples containing phosphorus compound and phosphrous compound/silicone compound was found to be passed the flame-retardant requirements (LOI: > 30%, UL 94-V: V-0) of LOI and vertical burning tests. However, the flame 영구적 난연성기를 함유한 에폭시 수지를 얻기 위하여, 본 연구에서는 디하이드록시를 함유한 인 화합물[10-(2,5-dihydroxyphenyl)- 9,10-dihydro-9-oxa-10-phospha phenanthrene-10-oxide, DOPO-HQ]과 디하이드록시를 함유한 실리콘 화합물(polydimethylsiloxane, hydroxyl terminated, PDMS)를 경화하지 않은 에폭시 프리폴리머(diglycidyl ether of bisphenol A, DGEBA)와 반응시킨 다음, 경화제(4,4-diaminodiphenylmethane, DDM)를 사용하여 경화반응 시킨 에폭시 수지를 제조하였다. 제조된 에폭시 수지의 각종 특성을 적외선 분광분석기(FTIR), 시차주사열량기(DSC), 열중량 분석기(TGA), 한계산소지수(LOI)/수직 연소 시험(UL 94-V test), 인장 및 충격 시험을 이용하여 분석하였다. 그리고 사용한 인 및 실리콘 화합물의 함량이 에폭시 경화물의 열적/ 기계적 성질 및 난연성에 미치는 영향을 조사하였다. 인 및 실리콘 성분이 함유된 에폭시 수지의 열적 및 기계적 물성이 단순 에폭시 수지의 물성에 비교하여 크게 향상되었다는 것을 알 수 있었다. 그리고 인 및 실리콘을 함유한 모든 에폭시 수지는 29.9 ~ 31.8%의 LOI 및 V-0 수준의 UL 94-V로 난연성 기준(LOI: 30% 이상, UL 94-V: V-0)을 통과한 반면, 단순 에폭시 수지는 LOI: 21.4% 및 UL 94-V: no rating으로 난연성 기준에 크게 못 미치는 것을 알 수 있었다.
Ultrafast Crystallization of Amorphous Silicon Thin Films by Using an Electron Beam Annealing Method
김창헌,임상우,정채환 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.64 No.8
An electron-beam annealing method has been adapted for rapid crystallization of p-typeamorphous-silicon thin films deposited by using an evaporation method. The amorphous phaseof silicon thin-film was crystallized by using an accelerating DC voltage higher than the 4.0 kVfor 120 s. From the crystalline properties, the nanocrystalline silicon thin film after electron-beamannealing showed mainly (111), (220), and (311) orientations and a crystalline volume fraction (Xc)of 93.6%. The crystalline properties improved with increasing DC voltage for rapid annealing times. The electron-beam annealing method can be a powerful method for achieving rapid crystallizationof amorphous materials.