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<P>CHDH (choline dehydrogenase) is an enzyme catalyzing the dehydrogenation of choline to betaine aldehyde in mitochondria. Apart from this well-known activity, we report here a pivotal role of CHDH in mitophagy. Knockdown of CHDH expression impairs CCCP-induced mitophagy and PARK2/parkin-mediated clearance of mitochondria in mammalian cells, including HeLa cells and SN4741 dopaminergic neuronal cells. Conversely, overexpression of CHDH accelerates PARK2-mediated mitophagy. CHDH is found on both the outer and inner membranes of mitochondria in resting cells. Interestingly, upon induction of mitophagy, CHDH accumulates on the outer membrane in a mitochondrial potential-dependent manner. We found that CHDH is not a substrate of PARK2 but interacts with SQSTM1 independently of PARK2 to recruit SQSTM1 into depolarized mitochondria. The FB1 domain of CHDH is exposed to the cytosol and is required for the interaction with SQSTM1, and overexpression of the FB1 domain only in cytosol reduces CCCP-induced mitochondrial degradation via competitive interaction with SQSTM1. In addition, CHDH, but not the CHDH FB1 deletion mutant, forms a ternary protein complex with SQSTM1 and MAP1LC3 (LC3), leading to loading of LC3 onto the damaged mitochondria via SQSTM1. Further, CHDH is crucial to the mitophagy induced by MPP+ in SN4741 cells. Overall, our results suggest that CHDH is required for PARK2-mediated mitophagy for the recruitment of SQSTM1 and LC3 onto the mitochondria for cargo recognition.</P>
V(z)곡선법을 이용한 코발트기 초내열합금강의 열화도 평가 유용성 유무를 고주파 초음파 탐촉자를 이용하여 실험적으로 검증 하였다. 코발트기 초내열 합금이 고온에서 장시간 노출되었을 때 일어나는 미세조직의 변화를 모사하기 위해서 인공열화를 실시하였다. 여로하에 미치는 초음파 음속의 영향을 고찰하고자 10MHz를 이용하여 펄스-에코법으로 종파의 음속을 측정하고 200MHz를 사용하여 V(z)곡선법으로 누설턴성표면파의 음속을 측정하였다. 두 초음파의 음속은 열화시간에 따라서 감소 하였다. 더욱이, 저주파수 종파의 음속변화는 거의 없었지만, 고주파수 누설탄성표면파의 음속변화는 열화시간에 따라서 최대 4.7%의 변화를 나타내었다. 열화에 따른 강도의 변화와 누설탄성표면파의 음속 변화는 양호한 상관관계를 나타내었다. 따라서 열화도 평가에 고주파 탐촉자를 이용한 초음파 현미경의 V(z)곡선법이 유용함을 알 수 있었다. The feasibility of V(z) curve method of scanning acoustic microscope using high frequency transducer was experimentally studied for assessment of the thermal degradation in Co-based superalloy. Thermal degradation was performed to simulate the microstructural changes in Co-based superalloy arising trom long term exposure at high temperature. Longitudinal wave velocity measured by pulse echo method using 10MHz transducer and leaky surface acoustic wave (LSAW) velocity measured by V(z) curve method using 200MHz transducer were measured to investigate the effect on thermal degradation. Ultrasonic velocity decreased as the aging time increased in both ultrasonic waves. Moreover, the low frequency longitudinal wave velocity decreased a little. Otherwise, the high frequency LSAW velocity drastically decreased up to a maximum of 4.7% at the aging time of 4,000hours. A good correlation was found between LSAW and Vickers hardness. Consequently, V(z) curve method of SAM using high frequency transducer could be a potential tool for assessing thermal degradation.
Accurate modeling of the transformer, including its saturation characteristics, is an important requirement for studying inrush current, overvoltage and ferroresonance conditions. This paper describes a straightforward method of determining the parameters for a standard T-type equivalent circuit representation of the transformer which can be used to predict the inrush current with good accuracy. The method relies on test measurements that can be readily performed on site: there is no need for design data on the transformer. A comparison of the computed waveforms with measured waveforms of the inrush currents of a distribution transformer is used to verify the accuracy of the method.
The purposes of this study are to investigate and survey the solutions for the dwelling Problem during apartment buildings' remodeling period. The research method of this study includes case studies and a questionnaire survey from apartment residents. Through the research 3 moving options are investigated based on case studies and questionnaire survey, and finally the selection priority of the options is suggested.
Frictional force tends to rapidly increase as the relative angle between the bracket slot and the archwire increases beyond critical contact angle. The purpose of this study was to measure the frictional forces between lingual orthodontic brackets and orthodontic archwires with a friction tester (FPR 2000, Rhesca, Japan). The influence of the presence of artificial saliva was determined additionally. Two different lingual brackets (FJT: Fujita, Japan; ORM: Ormco, USA) and one labial standard bracket (CTL:TOMY, Japan) as a control were used in this study. Archwires of three different alloys (SS: Stainless steel, Ormco, USA; TM: β-Titanium, Ormco, USA; EL: Cobalt-chrome, RMO, USA) with 0.016 x 0.022 inch and 0.017 x 0.025 inch were used in this study. Each bracket-archwire couple was tested with a friction tester in the dry and artificial saliva environments. Each measurement was conducted with a angular velocity of 0.1 rpm for 90 seconds under the normal force of 100gf at 25 ℃ for the dry and 34 ℃ for the artificial saliva environment. For SS and EL archwires, frictional force was greater with FJT bracket than with ORM bracket (p<0.01). Compared with SS and TM archwires, 0.016 x 0.022 inch EL archwire showed the greatest frictional forces with two lingual brackets (p<0.01). There were significant differences in frictional force between the dry and artificial saliva environment (p<0.05), however, the effects of artificial saliva were different depending on the bracket-archwire combinations. Experimental critical contact angles were greater than theoretically calculated values.
중성자 방사화법은 여러 가지 물질의 특성을 규명하는데 매우 유용한 방법이다. 기본적으로 이러한 방법은 매우 간단하다. 임의의 시료를 저속 중성자에 조사시키면, 그 시료는 방사능을 띄게 되고 시료로부터 나오는 β^+, β^-, 그리고 γ선의 선량을 측정하거나 시료의 반감기를 측정하면, 시료를 구성하고 있는 물질의 구성성분이나 그 농도를 알아낼 수 있다. 본 연구에서는 금 박막을 방사화시킴으로서 열중성자 선량값으로 1426.68 ± 11.62n/㎠ㆍsec를 얻었다. 또한, ^55Mn의 열중성자 포획 단면적은 13.79±0.45bam 이었는데 이는 Table of Isotope에 제시된 값과 매우 잘 일치하였다. 본 연구의 실험기법은 일반적으로 널리 알려진 방법이지만, 학생들이 쉽게 접할 수 있는 실험이 아니기 때문에 '선량' 또는 '단면적' 등돠 같은 물리 개념을 가르치는데 유용하게 사용될 수 있을 것으로 기대된다. Neutron activation is very powerful technique for identifying characteristics of many elements. Basically the technique is quite simple. A sample is irradiated by slow neutrons and becomes radioactive. By measuring the β^+s, β^-s, γs and half-life of the resulting sample, the elemental constituents of the sample and their relative concentrations can be identified. In this studies, thermal neutron flux was 1426.68 ± 11.62 n/㎠ ·sec from Au activation analysis. Thermal neutron capture cross section for ^55Mn was 13.79 ± 0.45 barn, it is a good agreement with Table of Isotope data. Technique of this measurement is not special, but can be used usefully for physics concepts learning such as flux and cross section.
발전설비의 보수검사에 적용하기 위한 예비 연구로 comb transducer를 이용한 파이프 내에서의 유도초음파 모드의 거동을 실험적으로 검증하였다. 유도초음파의 모드식별은 STFT와 WT에 의한 시간-주파수해석을 통하여 최적의 모드를 선정하였다. 시간-주파수해석과 이론적 해석 방법인 분산 곡선을 비교한 결과 잘 일치함을 알 수 있었으며, pitch-catch법과 선단부로부터 반사된 신호를 모두 분석한 결과 L(0,1) 모두가 다른 모드에 비해 모드변화에 의한 영향이 적었다. 따라서 L(0,1)을 최적의 모드로 선정하고, 결함위치를 추정한 결과 유용함을 알 수 있었다. A preliminary study of the behavior of ultrasonic guided wave mode in a pipe using a comb transducer for maintenance inspection of power plant facilities has been verified experimentally. The mode identification has been carried out in a pipe using the time-frequency analysis methods such as the wavelet transform(WT) and the short time Fourier transform (STFT), compared with theoretically calculated group velocity dispersion curves for longitudinal and flexural modes. The results are in good agreement with analytical predictions and show the effectiveness of using the time-frequency analysis method to identify the individual modes. It was found out that the longitudinal mode(0,l) is less affected by mode conversion compared with the other modes. Therefore, L(0,l) is selected as an optimal mode for the evaluation of the surface defect in a pipe.
발전설비의 중요한 요소인 배관의 효율적인 비파괴검사를 위해, 배관내에 유도초음파를 comb 트랜스듀서를 이용하여 발생시켰으며, 유도초음파를 비접촉 방식으로 수신하기 위해 ACT(air-coupled transducer)를 적용하였다. comb 트랜스듀서의 요소간격과 이론적인 분산선도로부터 발생가능 한 유도초음파 모드가 예측되었다. 또한 예측된 모드를 수신하기 위해 각 모드의 이론적인 위상속도를 이용하여 ACT의 수신 각도를 결정하였다. 수신모드의 특성을 규명하기 위해 웨이블릿 변환과 2D-FFT를 이용한 시간-주파수해석을 수행하여 이론적인 분산선도와 비교한 결과, 수신된 모드는 이론적으로 예측된 모드와 일치하는 것으로 나타났다. In order to inspect the piping effectively, one of the important components in the facility of power plants, the ultrasonic guided wave was generated by a comb transducer and was received in a non-contact fashion by using an air-coupled transducer. The guided wave modes that can be generated by the comb transducer in piping are predicted from the theoretical dispersion curves and the element spacing of a comb transducer. Moreover, to receive the specific modes, the receiving angle of the air-coupled transducer is calculated from Snell's law between the phase velocities of guided waves and the sound velocity of air. The guided wave modes obtained in experiments are identified from the result of time-frequency analysis such as wavelet transform and two-dimensional fast Fourier transform.
Prevertebral soft tissue swelling of cervical spine lateral radiogram is well known as an indirect evidence of occult cervical spine injury. But the clinical and statistical value of it has been of debate. We tried to analyse the value of cervical prevertebral soft tissue width as a screening test for cervical spine injury by comparison of two categorized study groups; the control group, traumatized patients without cervical spine injury and the injury and the injury group, traumatized patients with bony cervical injury. The injury group consisted of patients admitted between September 1993 and December 1994 with an ED diagnosis of bony cervical injury. The control group consisted of patients admitted between January 1994 and June 1994 who received cervical spine lateral radiograph because of suspicion of cervical spine injury or as a routine check. In both group, we sampled the patients who received cervical spine lateral rediograph within 24 hours after injury and excluded the patients less than 15 years old and more than 65 years old, In the control group, we confirmed the patients had no problem in cervical spine of follow-up. 101 control patients and 68 injury patients were identified. The injury group was further divided into two subgroups: those with injuries at C1-C3 to the upper injury subgroup and those with injuries at C4-C7 to the lower injury sub group. The prevertebral soft tissue widths of injury group were larger than of control group at C2(mean 6.1mm versus 4.5mm) and also at C6(mean 13.4mm versus 11.2mm). Especially upper injury subgroup had quite large value of C2 prevertebral soft tissue width(mean 14.1mm). Nevertheless, both in C2 and C6, there is no cutoff value with acceptable sensitivity and specificity as a screening test. But the 7mm at C2 and 14mm at C6 had high specificity(90%) and were thought to be a good radiologic indicators of further evaluation.
To determine the usefulness of application of Mitomycin-C (MMC) and effectiveness of different concentration of MMC in external DCR. A total of 100 eyes of 87 patients diagnosed with primary acquired nasolacrimal duct obstruction were assigned randomly to either a MMC group or control group. The surgical procedures in both groups were same. In MMC group, a piece of neurosurgical cottonoid soaked with 0.4 mg/ml MMC was applied to the osteotomy site and then was removed after 5 and 10 minutes differently. Nasoendoscopic examination was performed at 1 month, 3 months, and 6 months after surgery for all patients. The causes of epiphora as trauma (20 cases), failed DCR (1 case), sinus surgery (2 cases), unknown (77 cases). The overall anatomical success rate of the procedure was 88% and functional success rate was 79%. Obstruction site was related to anatomical surgical results. Anatomical surgical outcome at lower lacrimal sac level group of patients showed a statistically significant success rate, but functional surgical outcome showed no significant difference between the two groups. The anatomical success rate was 87.7% and the functional success rate was 84.2% in MMC group. The anatomical success rate was 88.3% and the functional success rate was 74.4% in control group. Application of MMC and it's application time were not related to surgical results.