• Journal of the Korean Vacuum Society
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• v.21 no.4
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• pp.219-224
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• 2012

We study for long-term performance of amorphous silicon solar cells under light exposure. The performance is predicted with a kinetic model in which the carrier lifetimes are determined by the defect density. In particular, the kinetic model is described by the stretched-exponential relaxation of defects to reach equilibrium. In this report, we simulate the light-induced degradation of the amorphous silicon solar cells with the kinetic model and AMPS-1D computer program. And data measured for outdoor performances of various solar cells are compared with the simulated results. This study focuses on examining the light-induced degradation for the following amorphous silicon pin solar cells: thickness${\approx}$300 nm, built-in potential${\approx}$1.05 V, defect density (at t=0)${\approx}5{\times}10^{15}cm^{-3}$, short-circuit current density (at t=0)${\approx}15.8mA/cm^2$, fill factor (at t=0)${\approx}0.691$, open-circuit voltage (at t=0)${\approx}0.865V$, conversion efficiency (at t=0)${\approx}9.50%$.

• Korean Journal of Radiology
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• v.20 no.5
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• pp.791-800
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• 2019

Objective: To compare various models of diffusion-weighted imaging including monoexponential apparent diffusion coefficient (ADC), biexponential (fast diffusion coefficient [D_f], slow diffusion coefficient [D_s], and fraction of fast diffusion), stretched-exponential (distributed diffusion coefficient and anomalous exponent term [α]), and kurtosis (mean diffusivity and mean kurtosis [MK]) models in the differentiation of renal solid masses. Materials and Methods: A total of 81 patients (56 men and 25 women; mean age, 57 years; age range, 30-69 years) with 18 benign and 63 malignant lesions were imaged using 3T diffusion-weighted MRI. Diffusion model selection was investigated in each lesion using the Akaike information criteria. Mann-Whitney U test and receiver operating characteristic (ROC) analysis were used for statistical evaluations. Results: Goodness-of-fit analysis showed that the stretched-exponential model had the highest voxel percentages in benign and malignant lesions (90.7% and 51.4%, respectively). ADC, D_s, and MK showed significant differences between benign and malignant lesions (p < 0.05) and between low- and high-grade clear cell renal cell carcinoma (ccRCC) (p < 0.05). α was significantly lower in the benign group than in the malignant group (p < 0.05). All diffusion measures showed significant differences between ccRCC and non-ccRCC (p < 0.05) except D_f and α (p = 0.143 and 0.112, respectively). α showed the highest diagnostic accuracy in differentiating benign and malignant lesions with an area under the ROC curve of 0.923, but none of the parameters from these advanced models revealed significantly better performance over ADC in discriminating subtypes or grades of renal cell carcinoma (RCC) (p > 0.05). Conclusion: Compared with conventional diffusion parameters, α may provide additional information for differentiating benign and malignant renal masses, while ADC remains the most valuable parameter for differentiation of RCC subtypes and for ccRCC grading.

• Journal of Korean Physical Therapy Science
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• v.3 no.3
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• pp.87-91
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• 1996

Until the up to day, we have known that a tight iliotibial tract has an influence on the patella, pulling it laterally and causing pain in patients with patellofemoral syndrome, so should be stretched as a part of physical therapy. But the iliotibial tract's function on the patella in subjects with PFS has not yet been proved and further questions need to be answered regarding the evlauation or treatment of a tight tract in patients with PFS.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.249-251
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• 2005

For walking patterns of biped robots, knee-bent patterns are used in most cases. However, humans are mostly walking with their knees nearly stretched. In this paper, a human-like walking algorithm using hybrid system is proposed for biped robots, The hybrid system consists of the logically constituted discrete system, in which the discrete states are defined by considering the walking characteristics, and the continuous state system used for motor control. It is shown that the proposed algorithm is effective by experimental studies.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2002.10a
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• pp.266-267
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• 2002

실뱀장어 재료는 1998년 한국의 제주도 천제연, 낙동강 그리고 금강 하구 세 곳에서 실뱀장어 주 소상 시기 3개월 동안 채집하였다 실뱀장어는 조류가 강하고 어두운 밤에 활동성이 강하므로 각 월의 그믐 때 채집하였다. 제주도 천제연 하구에서는 손전등으로 빛을 비추고 뜰채(dip nets)를 이용해 채집하였다. 채집에 이용된 뜰채는 망직경이 20cm 정도이며 망목(stretched mesh width)은 1 mm 이었다. (중략)

• Proceedings of the Korean Fiber Society Conference
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• 2001.10a
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• pp.355-358
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• 2001

Copolyetheresters are us,ed as an engineering thermoplastic elastomer due to their excellent mechanical properties, thermooxidative stability up to high temperatures and a good resistance against many chemicals. However, fibers made from the copolyetheresters exhibited elastic recovery of about 80-85％ after being stretched 200％, while spandex fibers usually showed 90-95％ recovery. (omitted)

• Korean Journal of Applied Biomechanics
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• v.13 no.3
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• pp.99-116
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• 2003

The purpose of this study was to kinematics factors on during round-off at end of beam-salto backward stretched with step-out to cross on balance beam. Four elite female gymnastics players participated as subject of this study. The methods of this study was analyzed using three dimentional analysis. The results and conclusion of this paper is obtained as follows ; 1. The phase of time was the most short time in board touch down phase and board take-off phase. Also, it was shown a more long time in total time compared to previous study. 2. The horizontal displacement of each phase was shown the most high levels in balance beam landing. The vertical displacement was display a non-linearity increase in board take-of phase, and it was shown the most high levels in vertical displacement during landing of balance beam. 3. The horizontal velocity of each phase was shown the most high levels in board touch down, and it was display a gradually decreased levels because flight during board take-of. The resultant velocity of CG on each phase was shown the most high levels in board touch down and board take-off. 4. The angle of hip joint was shown the most high levels as performed a motion in extension state during board take-off, and the angle of knee joint was display a increased levels because of flight cause body extension in board take-off. Also the angle of ankle joint was shown a increasing levels during board take-off. Considering to this results, it is suggest that the change of kinematics factors in board touch down and board take-off is key role on the effective board control.

• Journal of the Korean Society of Physical Medicine
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• v.5 no.4
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• pp.527-534
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• 2010

Purpose : The application of tape to modulation of pain and muscular excitability has become common clinical practice among musculoskeletal physical therapy. However, the techniques of the tape application has been relied on empirical evidence in preference to the neurophysiological evidence. Thus, the mechanism of taping has to be elucidated further. The aim of this study was to determine whether elastic and non-elastic taping across a muscle does indeed change ${\alpha}$-motor neuron excitability. Methods : The study was performed on 10 neurologically healthy adults. Two different types of tape were applied to skin overlying gastrocnemius. The elastic tape stretched up to 120% of its original length but non-elastic tape didn't stretched up of its original length. The tape applied across the direction on thickest part of the gastrocnemius. The ${\alpha}$-motor neuron excitability of the gastrocnemius was assessed using the gastrocnemius H-reflex. The amplitude of the M-wave and H-reflex were measured across three conditions: before tape application, with tape and with the tape removed. Results : No significant changes of the excitability of the ${\alpha}$-motor neuron were obtained across three condition, either in the elastic and non-elastic tape. Conclusion : From the results, I could come to the conclusion that further clinical work will be required.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.43 no.4
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• pp.49-58
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• 2011

The maximum drying shrinkage velocity was proposed to verify bulk and stiffness improvement mechanism during drying according to papermaking parameters. It was based on the wet-web shrinkage behavior without the restraint of wet-web during drying, so intact drying impact could be measured. Bulking agent reduced the drying shrinkage and the maximum drying shrinkage velocity, so paper bulk increased and paper strength decreased. When adding cationic starch to stock with the bulking agent for strengthening, the bulk was increased further with additional decreasing of the drying shrinkage and the maximum drying shrinkage velocity. Paper strength also increased except tensile stiffness index with decreasing the drying shrinkage and the maximum drying shrinkage velocity. When using additional strength additives for strengthening of fiber interfaces extended by bulking agent and cationic starch, amphoteric strength additive increased paper stiffness without loss of paper bulk. It was considered that the added amphoteric strength additives were cross-linked to the stretched cationic starch and this cross-linking increased elasticity of fiber-polymer-fiber interfaces without changing the drying behavior. Paper bulk could be increased with decreasing the maximum drying shrinkage velocity. The drying shrinkage of paper also could be controlled by fiber-to-fiber bonding interfaces by the bulking agent. In this case, paper strength including stiffness was decreased by reducing fiber-to-fiber bonding but it could be improved by strengthening fiber-to-fiber interfaces with polymer complex without loss of bulk.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.10
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• pp.1146-1152
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• 2011

Ink transfer process is very important to determine quality of printed pattern, therefore its mechanism should be understood to control printing quality. Although there have been many attempts to understand ink transfer mechanism by numerical simulation and experimental studies, their model was too much simple to model realistic printing process and our understanding is not enough yet. In this paper we designed ink transfer visualization system to present flow visualization of ink transfer process for gravure offset printing. We considered rotational effect of blanket roll which is related with printing speed and used non-Newtonian fluid as working fluid such as Ag paste. For printing unit, cantilever-type blanket roll is used for convenient visualization of ink transfer. Serial images were captured continuously by using high-speed CMOS camera and long range microscope. We investigated the effects of various design parameters such as printing speed and pattern angle on the ink transfer process. We found more stretched ink filament for non-Newtonian fluid than Newtonian fluid. As increasing printing speed, length of stretched ink filament and height of break-up point are also increased. We also compared ink transfer process between CD and MD pattern and its relationship with ink transfer mechanism.