• Current Applied Physics
• /
• 제18권12호
• /
• pp.1564-1570
• /
• 2018

Charge transport dynamics in ZnO based inverted organic solar cell (IOSC) has been characterized with transient photocurrent spectroscopy and localised photocurrent mapping-atomic force microscopy. The value of maximum exciton generation rate was found to vary from $2.6{\times}10^{27}m^{-3}s^{-1}$ ($J_{sat}=79.7A\;m^{-2}$) to $2.9{\times}10^{27}m^{-3}s^{-1}$ ($J_{sat}=90.8A\;m^{-2}$) for devices with power conversion efficiency ranging from 2.03 to 2.51%. These results suggest that nanorods served as an excellent electron transporting layer that provides efficient charge transport and enhances IOSC device performance. The photovoltaic performance of OSCs with various growth times of ZnO nanorods have been analysed for a comparison between AM1.5G spectrum and local solar spectrum. The simulated PCE of all devices operating under local spectrum exhibited extensive improvement with the gain of 13.3-3.7% in which the ZnO nanorods grown at 15 min possess the highest PCE under local solar with the value of 2.82%.

• Clinics in Shoulder and Elbow
• /
• 제23권4호
• /
• pp.183-189
• /
• 2020

Background: The purpose of the current study was to investigate short- to mid-term outcomes and complications following radial head replacement (RHR) for complex radial head fractures and to identify factors associated with clinical outcomes. Methods: Twenty-four patients with complex radial head fractures were treated by RHR. The mean age of the patients was 49.8 years (range, 19-73 years). Clinical and radiographic outcomes were evaluated for a mean follow-up period of 58.9 months (range, 27-163 months) using the visual analog scale (VAS) score for pain, the Mayo elbow performance score (MEPS), the quick disabilities of the arm, shoulder and hand (Quick-DASH) score, and serial plain radiographs. Complications were also evaluated. Results: At the final follow-up, the mean VAS score, MEPS, and Quick-DASH score were 0.6±1.1, 88.7±11.5, and 19.4±7.8, respectively. The mean range of motion was 132.7° of flexion, 4.7° of extension, 76.2° of pronation, and 77.5° of supination. Periprosthetic lucency was observed in six patients (25%). Heterotopic ossification was observed in four patients (16.7%). Arthritic change of the elbow joint developed in seven patients (29.2%). Capitellar wear was found in five patients (20.8%). Arthritic change of the elbow joint was significantly correlated with MEPS (P=0.047). Four cases of complications (16.6%) were observed, including two cases of major complications (one stiffness with heterotopic ossification and progressive ulnar neuropathy and one stiffness) and two cases of minor complications (two transient ulnar neuropathy). Conclusions: RHR for the treatment of complex radial head fractures yielded satisfactory short- to mid-term clinical outcomes, though radiographic complications were relatively high.

• Advances in nano research
• /
• 제10권2호
• /
• pp.151-163
• /
• 2021

The main target of this study is to investigate nonlinear transient responses of moving polymer nano-size plates fortified by means of Graphene Platelets (GPLs) and resting on a Winkler-Pasternak foundation under a transverse pressure force and a temperature variation. Two graphene spreading forms dispersed through the plate thickness are studied, and the Halpin-Tsai micro-mechanics model is used to obtain the effective Young's modulus. Furthermore, the rule of mixture is employed to calculate the effective mass density and Poisson's ratio. In accordance with the first order shear deformation and von Karman theory for nonlinear systems, the kinematic equations are derived, and then nonlocal strain gradient scheme is used to reflect the effects of nonlocal and strain gradient parameters on small-size objects. Afterwards, a combined approach, kinetic dynamic relaxation method accompanied by Newmark technique, is hired for solving the time-varying equation sets, and Fortran program is developed to generate the numerical results. The accuracy of the current model is verified by comparative studies with available results in the literature. Finally, a parametric study is carried out to explore the effects of GPL's weight fractions and dispersion patterns, edge conditions, softening and hardening factors, the temperature change, the velocity of moving nanoplate and elastic foundation stiffness on the dynamic response of the structure. The result illustrates that the effects of nonlocality and strain gradient parameters are more remarkable in the higher magnitudes of the nanoplate speed.

• 반도체디스플레이기술학회지
• /
• 제21권2호
• /
• pp.123-126
• /
• 2022

We investigated deep levels in n-type 4H-SiC epitaxy layer of the Positive-Intrinsic-Negative diode and Schottky barrier diodes by using deep level transient spectroscopy. Despite the excellent performance of 4H-SiC, research on various deep level defects still requires a lot of research to improve device performance. In Positive-Intrinsic-Negative diode, two defects of 196K and 628K are observed more than Schottky barrier diode. This is related to the action of impurity atoms infiltrating or occupying the 4H-SiC lattice in the ion implantation process. The I-V characteristics of the Positive-Intrinsic-Negative diode shows about ~100 times lower the leakage current level than Schottky barrier diode due to the grid structures in Positive-Intrinsic-Negative. As a result of comparing the capacitance of devices diode and Schottky barrier diode devices, it can be seen that the capacitance value lowered if it exists the P implantation regions from C-V characteristics.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• 제49권1호
• /
• pp.2-12
• /
• 2023

The current study aimed to explore the types and frequencies of uncommon complications associated with third molar extractions based on a scoping review of case reports and case series. The study used an electronic literature search based on PubMed and Embase up to March 31, 2020, with an update performed on October 22, 2021. Any case reports and case series that reported complications associated with third molar extractions were included. The types of complications were grouped and the main symptoms of each type of complication were summarized. A total of 51 types of uncommon complications were identified in 248 patients from 186 studies. Most types of complications were post-operative. In the craniofacial and cervical regions, the most frequent complications included iatrogenic displacement of the molars or root fragments in the craniofacial area, late mandibular fracture, and subcutaneous emphysema. In other regions, the most frequent complications include pneumomediastinum, pneumorrhachis, pneumothorax, and pneumopericardium. Of the patients, 37 patients had life-threatening uncommon complications and 20 patients had long-term/irreversible uncommon complications associated with third molar extractions. In conclusion, a variety of uncommon complications associated with third molar extractions were identified. Most complications occurred in the craniofacial and cervical regions and were mild and transient.

• Korean Circulation Journal
• /
• 제53권4호
• /
• pp.239-250
• /
• 2023

Background and Objectives: Brugada syndrome (BrS) is an inherited arrhythmia syndrome that presents as sudden cardiac death (SCD) without structural heart disease. One of the mechanisms of SCD has been suggested to be related to the uneven dispersion of transient outward potassium current (I_to) channels between the epicardium and endocardium, thus inducing ventricular tachyarrhythmia. Artemisinin is widely used as an antimalarial drug. Its antiarrhythmic effect, which includes suppression of I_to channels, has been previously reported. We investigated the effect of artemisinin on the suppression of electrocardiographic manifestations in a canine experimental model of BrS. Methods: Transmural pseudo-electrocardiograms and epicardial/endocardial transmembrane action potentials (APs) were recorded from coronary-perfused canine right ventricular wedge preparations (n=8). To mimic the BrS phenotypes, acetylcholine (3 μM), calcium channel blocker verapamil (1 μM), and I_to agonist NS5806 (6-10 μM) were used. Artemisinin (100-150 μM) was then perfused to ameliorate the ventricular tachyarrhythmia in the BrS models. Results: The provocation agents induced prominent J waves in all the models on the pseudo-electrocardiograms. The epicardial AP dome was attenuated. Ventricular tachyarrhythmia was induced in six out of 8 preparations. Artemisinin suppressed ventricular tachyarrhythmia in all 6 of these preparations and recovered the AP dome of the right ventricular epicardium in all preparations (n=8). J wave areas and epicardial notch indexes were also significantly decreased after artemisinin perfusion. Conclusions: Our findings suggest that artemisinin has an antiarrhythmic effect on wedge preparation models of BrS. It might work by inhibition of potassium channels including I_to channels, subsequently suppressing ventricular tachycardia/ventricular fibrillation.

• Nuclear Engineering and Technology
• /
• 제56권6호
• /
• pp.2011-2018
• /
• 2024

Since RF breakdown is one of the primary limitations to improving the performances of RF accelerators, extensive efforts have been dedicated to locating the breakdowns. However, most existing methods rely on specialized techniques, resulting in high financial burdens. Although the method based on transient response of transmission line (TL) is suitable for facilities with sporadic recoverable breakdowns, practical operations are susceptible to notable errors. This study revisits the fundamental theories of lossless TL and investigates the wave process to understand the characteristics of the reversed pulse induced by the breakdowns. By utilizing steadystate response of the TL and employing phasor method, we derive analytical formulas to determine the exact location of breakdowns within the faulty cell for constant-gradient TW accelerator. Furthermore, the derived formulas demonstrate their independence from RF phase, thereby distinguishing them from traditional phasebased methods. Additionally, experimental validations are conducted at the HUST injector, and the results confirm the consistency of the analysis. Thus, the proposed method represents a promising improvement over the TL-based approaches and serves as a valuable complement to current techniques. Importantly, this method demonstrates particular advantages for constructed TW accelerators seeking to achieve a balance among high performance, low costs, and compact layouts.

• 한국구조물진단유지관리공학회 논문집
• /
• 제12권6호
• /
• pp.164-172
• /
• 2008

초기 재령의 매스콘크리트는 양생과정에서 높은 온도를 유발한다. 수화열 저감 기법 중 내부구속이 지배적인 구조물에서 단면의 내외부 온도차를 관리하는 방식은 그 활용도가 매우 높다. 그러나 수화 균열을 예방하기위해 열경사를 조절하는 현재의 제한적인 방법은 콘크리트 중심과 표면 사이에 미세하거나 거대한 균열을 유발할 수 있다. 특히 냉각파이프를 이용하는 방법은 온도의 상승시에는 적용될 수 있지만, 내외부 온도차이가 심한 온도하강시의 대책으로는 적합하지 않다. 따라서 이 문제에 대한 해결방안으로 가열파이프를 동시에 사용하는 모델을 제안하여 유한요소법으로 해석하였다. 해석 결과, 제안된 냉각파이프와 가열파이프를 동시에 사용하는 방법이 열경사조절에 가장 효과적이며 이를 통해 온도균열을 효과적으로 제어할 수 있을 것으로 판단된다.

• 조명전기설비학회논문지
• /
• 제20권4호
• /
• pp.21-28
• /
• 2006

본 논문에서는 Ballard사의 1.2[kW]급 연료전지와 연료전지의 저전압($28{\sim}43[VDC]$)을 승압(380([VDC])시키기 위한 풀-브리지 직류-직류 컨버터, 그리고 승압된 직류 링크전압을 교류 전압(220[VAC]), 60[Hz]으로 변환하기 위한 단상 풀-브리지 인버터로 구성된 연료전지 발전용 전력변환시스템 중 풀-브리지 고주파 절연형 영전압 영전류 스위칭 위상 천이 펄스폭 변조 직류-직류 컨버터를 제안하였다. 제안한 풀-브리지 고주파 절연형 영전압 영전류 스위칭 위상 천이 펄스폭 변조 직류-직류는 프리휠링 다이오드를 포함한 탭부 인덕터 필터를 이용하여 순환 전류를 저감시켰으며, 스위치 및 변압기의 턴-온, 턴-오프시에 오버슈트 전압이나 과도현상이 발생하지 않는다. 그리고 넓은 출력 전압 조정에도 효율을 $93{\sim}97[%]$정도 얻을 수 있으며, 출력 부하전류의 변화에 대해 거의 일정한 출력 전압 특성을 가졌다.

• 한국한의학연구원논문집
• /
• 제13권2호통권20호
• /
• pp.65-69
• /
• 2007

Background and Purpose : The purpose of this case-control study was to show the relationship between risk factors(past medical history, BMI, WHR, smoking, drinking), warning signs(dyscinesia, sightless, dysarthria, sensory disorder, numbness, blephalospasm, facial spasm, tension) and the incidence of stroke in korean adults. Methods : 455 stroke patients were enrolled as the case group and 180 non-stroke patients as control group from Oct. 2005 to Feb. 2006. Patients were hospitalized within 2 weeks after the onset of stroke. Obesity were defined as $BMI{\geq}25kg/m2$, $WHR{\geq}0.9$ in male and $WHR{\geq}0.8$ in female. Risk factors and warning signs were obtained from personal interview. The analysis of the data was done by chi-square test. Fisher's exact test and test-sample t-test. Results : The percentage of current smokers(or current drinkers) of case group is higher significantly than that of control group. The past medical history of risk factors were found to be transient ischemic attack(p=0.0698), facial palsy(p=0.4061), hypertension(p<0.0001), hyperlipidemia(p=0.1484), DM(p<0.0001), ischemic heart disease(p=0.0093), migraine(p=0.0014) and hypochondria(p=0.2370). $WHR{\geq}0.9$ in male had a 6.696 (3.711-12.082) odds ratio, $WHR{\geq}0.8$ in female had a 1.567 (0.659-3.726) odds ratio. $BMI{\geq}25kg/m2$ had a 2.017(1.263-3.222). The dyscinesia and sensory disorder of warning signs were found to be statistical difference between case and control group. Conclusions : According to the above results, it was found that smoking, drinking, BMI, WHR, hypertension, DM, ischemic heart disease, migraine affected to the incidence of stroke.