• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.5
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• pp.471-478
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• 2010

Thin films play an important role in many technological applications including microelectronic devices, magnetic storage media, MEMS and surface coatings. It is well known that a thin film's material properties can be very different from the corresponding bulk properties and thus there has been a strong need for the development of a reliable test method to measure the mechanical properties of a thin film. We have developed an alternative and convenient test method to overcome the limitations of previous membrane deflection experiment and uniaxial tensile test by adopting a white light interferometer having sub-nanometer out-of-plane displacement resolution. The freestanding aluminium specimens are tested to verity the effectiveness of the test method developed and get the tensile properties. The specimens are 0.5 rum wide, $1{\mu}m$ thick and fabricated through MEMS processes including sputtering. 1 to 5 specimens are fabricated on Si dies. The membrane deflection experiments are carried out by using a homemade tester consisted of a motor-driven loading tip, a load cell, and 6 DOF alignment stages. The test system is compact enough to set it up beneath a commercial white light interferometric microscope. The white light fringes are utilized to align a specimen with the tester. The Young's modulus and yield point stress of the aluminium film are 62 GPa and 247 MPa, respectively.

• Journal of the Korean Society for Nondestructive Testing
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• v.28 no.1
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• pp.16-24
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• 2008

Near-field scanning microwave microscope (NSMM) has been used to characterize the electromagnetic properties of samples based on a cavity perturbation technique. We used a NSMM using a waveguide cavity to couple a metallic probe tip as a point like evanescent field emitter. We explained the quality of our NSMM system by applying the cavity perturbation theory. First, to make a shape perturbation, we inserted linear and loop probes in the waveguide resonator. To check up electric and magnetic field distribution inside the waveguide resonator by shape perturbation, we confirmed the field distribution by using a HFSS simulation. Second, to make material perturbation, we located a dielectric sample in front of the probe tip and measured reflection coefficient $(S_{11})$. We found that the resonance frequency$(f_r)$ was changed linearly as the dielectric constant of resonator$({\varepsilon}_r)$ increased when ${\Delta}{\varepsilon}\;and\;{\Delta}{\mu}$ were small.

• Journal of Sericultural and Entomological Science
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• v.46 no.1
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• pp.23-27
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• 2004

We were investigated the cognitive ability enhancement in rats using B. mori fibroin molecular controlled hydrolysate by preparative recycle HPLC system. Also, some of its physicochemical properties and free amino acid components were investigated, too. Nuclear magnetic resonance (NMR) spectrum are measured different pattern between high (HF) and low (LF) molecular controlled B. mori fibroin samples, respectively. The in vitro test by neuron primary cell culture are showed dependent on molecular weight (Mw) of B. mori fibroin in the order of LF > MF > HF, too. However, the memorial effects in rats by in vivo test are large dependent molecular weight on that maximum 50% than control. Also, the memorial effect was higher than the enzymatic relative and acid hydrolysate, which was 50.0$\pm$2.1 and 25.9$\pm$0.32%, respectively.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.162-162
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• 1999

초고주파 집적회로의 핵심소자로 각광을 받고 있는 GaAs MESFET(MEtal-emiconductor)은 게이트 형성 공정이 가장 중요하며, WNx 내화금속을 이용한 planar 게이트 구조의 경우 임계전압(Vth:threshold voltage)의 균일도가 우수할 뿐만 아니라 특히 Side-wall을 이용한 self-align 게이트는 소오스 저항을 줄일 수 있어 고성능의 소자 제작을 가능하게 한다.(1) 본 연구의 핵심이 되는 Side-wall을 형성하기 위하여 PECVD법에 의한 SiOx 박막을 증착하고, 건식식각법을 이용하여 SiOx side-wall을 형성하였다. 이 공정을 이용하여 소오스 저항이 낮고 임계전압의 균일도가 우수한 고성능의 self-aligned gate MESFET을 제작하였다. 3inch GaAs 기판상에 이온주입법에 의한 채널 형성, d.c. 스퍼터링법에 의한 WNx 증착, PECVD법에 의한 SiOx 증착, MERIE(Magnetic Enhanced Reactive Ion Etcing)에 의한 Side-wall 형성, LDD(Lightly Doped Drain)와 N+ 이온주입, 그리고 RTA(Rapid Thermal Annealing)를 사용하여 활성화 공정을 수행하였다. 채널은 40keV, 4312/cm2로, LDD는 50keV, 8e12/cm2로 이온주입하였고, 4000A의 SiOx를 증착한 후 2500A의 Side-wall을 형성하였다. 옴익 접촉은 AuGe/Ni/Au 합금을 이용하였고, 소자의 최종 Passivation은 SiNx 박막을 이용하였다. 제작된 소자의 전기적 특성은 hp4145B parameter analyzer를 이용한 전압-전류 측정을 통하여 평가하였다. Side-wall 형성은 0.3$\mu\textrm{m}$ 이상의 패턴크기에서 수직으로 잘 형성되었고, 본 연궁에서는 게이트 길이가 0.5$\mu\textrm{m}$인 MESFET을 제작하였다. d.c. 특성 측정 결과 Vds=2.0V에서 임계전압은 -0.78V, 트랜스컨덕턴스는 354mS/mm, 그리고 포화전류는 171mA/mm로 평가되었다. 특히 본 연구에서 개발된 트랜지스터의 게이트 전압 변화에 따른 균일한 트랜스 컨덕턴스의 특성은 RF 소자로 사용할 때 마이크로 웨이브의 왜곡특성을 없애주기 때문에 균일한 신호의 전달을 가능하게 한다. 0.5$\mu\textrm{m}$$\times$100$\mu\textrm{m}$ 게이트 MESFET을 이용한 S-parameter 측정과 Curve fitting 으로부터 차단주파수 fT는 40GHz 이상으로 평가되었고, 특히 균일한 트랜스컨덕턴스의 경향과 함께 차단주파수 역시 게이트 바이어스, 즉 소오스-드레스인 전류의 변화에 따라 균일한 값을 보였다. 본 연구에서 개발된 Side-wall 공정은 게이트 길이가 0.3$\mu\textrm{m}$까지 작은 경우에도 사용가능하며, WNx self-align gate MEESFET은 낮은 소오스저항, 균일한 임계전압 특성, 그리고 높고 균일한 트랜스 컨덕턴스 특성으로 HHP(Hend-Held Phone) 및 PCS(Personal communication System)와 같은 이동 통신용 단말기의 MMICs(Monolithic Microwave Integrates Circuits)의 제작에 활용될 것으로 기대된다.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.7
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• pp.115-124
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• 2017

The objective of study was to investigate the optimal echo phase for mouse brain enhancement scan using fast low angle shot (FLASH) sequence of 9.4T magnetic resonance imaging (MRI). For quantification based on this method, an MR phantom experiment and clinical research were done. The phantom experiment was conducted by fabricating three phantoms with different molar concentration of gadolinium to create changes in echo phase of 9.4T FLASH sequence used in mouse brain scans. In the phantom experiment, SSI was 25~27 [arbitrary units, a.u.] in each of 33 phases from $6{\pi}$ to $28{\pi}$, while RSP was 30~100 mmol. MPSI was 47~52 [a.u], while MPP, where MPSI is seen, was 0.8~9 mmol. EPMS was 80.8~108.0%, while ASIMP was formed between 21.1 and 31.8 [a.u]. In the clinical research, Finally, the occurrence rate of artifact that expressed -1 nd +1. The present study was able to quantify the degree of enhancement at FLASH sequence of 9.4T MRI, as well as identify the optimal echo phase during mouse brain enhancement scan.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.12
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• pp.5019-5024
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• 2015

Background: The purpose of this study was to assess the dosimetric and clinical feasibility of volumetric modulated arc based hypofractionated stereotactic radiotherapy (RapidArc) treatment for large acoustic schwannoma (AS >10cc). Materials and Methods: Ten AS patients were immobilized using BrainLab mask. They were subject to multimodality imaging (magnetic resonance and computed tomography) to contour target and organs at risk (brainstem and cochlea). Volumetric modulated arc therapy (VMAT) based stereotactic plans were optimized in Eclipse (V11) treatment planning system (TPS) using progressive resolution optimizer-III and final dose calculations were performed using analytical anisotropic algorithm with 1.5 mm grid resolution. All AS presented in this study were treated with VMAT based HSRT to a total dose of 25Gy in 5 fractions (5fractions/week). VMAT plan contains 2-4 non-coplanar arcs. Treatment planning was performed to achieve at least 99% of PTV volume (D99) receives 100% of prescription dose (25Gy), while dose to OAR's were kept below the tolerance limits. Dose-volume histograms (DVH) were analyzed to assess plan quality. Treatments were delivered using upgraded 6 MV un-flattened photon beam (FFF) from Clinac-iX machine. Extensive pretreatment quality assurance measurements were carried out to report on quality of delivery. Point dosimetry was performed using three different detectors, which includes CC13 ion-chamber, Exradin A14 ion-chamber and Exradin W1 plastic scintillator detector (PSD) which have measuring volume of $0.13cm^3$, $0.009cm^3$ and $0.002cm^3$ respectively. Results: Average PTV volume of AS was 11.3cc (${\pm}4.8$), and located in eloquent areas. VMAT plans provided complete PTV coverage with average conformity index of 1.06 (${\pm}0.05$). OAR's dose were kept below tolerance limit recommend by American Association of Physicist in Medicine task group-101(brainstem $V_{0.5cc}$ < 23Gy, cochlea maximum < 25Gy and Optic pathway <25Gy). PSD resulted in superior dosimetric accuracy compared with other two detectors (p=0.021 for PSD.

• Clinical and Experimental Pediatrics
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• v.53 no.2
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• pp.262-266
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• 2010

Tumor necrosis $factor-{\alpha}$ ($TNF-{\alpha}$) is a major proinflammatory cytokine involved in the pathophysiology of juvenile rheumatoid arthritis. Etanercept is an effective inhibitor of $TNF-{\alpha}$ and has shown a beneficial effect in patients with JRA. However, the most important cause of concern related to etanercept administration is infection. We report a case of encephalitis in a JRA patient receiving long-term treatment with etanercept. The patient was a 4-year-old boy with refractory JRA, and he received etanercept subcutaneously at a dose of $0.4\;mg\;kg^{-1}\;day^{-1}$ twice a week for 14 months, along with non-steroidal anti-inflammatory drugs, methotrexate, oral steroids, and sulfasalazine. The patient presented with sudden fever, headache, vomiting, a generalized tonic seizure, and changes in mental status. We suspected a central nervous system infection, and simultaneously administered antibiotics, an antiviral agent, and steroids. After 2 days of hospitalization, his mental function returned to normal, and he showed no further seizure-like movements. Brain magnetic resonance imaging scan of the patient showed a multifocal cortical lesion on both sides of the temporoparietooccipital lobe, which indicated encephalitis. Although we were unable to identify the causative organism of encephalitis, we think that the encephalitis may be attributed to infection, and the use of etanercept may have increased the risk of severe infection. Therefore, etanercept was discontinued and the patient recovered shortly after. To the best of our knowledge, this is the first case of encephalitis in a juvenile rheumatoid arthritis patient treated with etanercept.

• Journal of Korean Neurosurgical Society
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• v.44 no.1
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• pp.26-35
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• 2008

Objective : In the evaluation of patients with Parkinson's disease (PD), most neurologists only see their patients during a limited period of their fluctuating 24-hour-a-day lives. This study aimed to assess the short-term outcome of STN stimulation for patients with advanced PD evaluated in a 24-hour monitoring unit for movement disorder (MUMD) using a prospective protocol. Methods : Forty-two patients with advanced PD consecutively treated with bilateral STN stimulation using multi-channel microelectrode recording were included in this study. All patients were evaluated using a 24-hour MUMD with a video recording/editing system and were evaluated with a prospective protocol of the Unified Parkinson's Disease Rating Scale, Hoehn and Yahr Staging, Schwab and England Activities of Daily Living, levodopa equivalent daily dose (LEDD), Short Form-36 Health Survey, and neuropsychological tests. Magnetic resonance (MR) images of the brain were performed prior to and six months after surgery. Results : All patients were evaluated at three and six months after surgery. There was a rapid and significant improvement of the motor symptoms, especially in tremor and rigidity, after STN stimulation with low morbidity. Dyskinesia was markedly decreased with much lowered LEDD values by 50% after STN stimulation. 1.5T MR images were safely taken according to the manufacturer's guidelines at six months after surgery without any adverse effects in 41 patients treated with STN stimulations. Conclusion : Evaluations in a 24-hour monitoring unit could reduce the dose of medication efficiently to an optimal level with patients' comfort and improve the clinical symptoms in harmony with STN stimulation.

• Journal of the Korean Arthroscopy Society
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• v.16 no.2
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• pp.140-146
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• 2012

Purpose: The objective of this study was to assess the clinical outcome of arthroscopic release of the extensor carpi radialis brevis (ECRB) tendon in chronic recalcitrant lateral epicondylitis and tried to determine any prognostic factors. Materials and Methods: A retrospective review of 24 patients with lateral epicondylitis treated by arthroscopic ECRB release was performed. Outcome measures included a patient self rating and visual analog scale (VAS). Functional evaluation was made with Quick-disabilities of the arm, shoulder and hand (DASH) score system to identify preoperative factors that might be associated with the outcomes. Results: Twenty one (88%) elbows received benefit from the procedure. A mean preoperative VAS pain score and the mean Quick-DASH were significantly improved at final follow up. Age, sex, dominant arm and duration of symptom, presence of capsular tear or calcification did not correlate significantly with the clinical outcome. Three of four patients without T2-weighted high signal focus of the ECRB origin on preoperative magnetic resonance imaging (MRI) showed higher Quick-DASH score. Conclusion: Arthroscopic release of the ECRB is an effective option for chronic recalcitrant lateral epicondylitis. Lack of high signal focus on preoperative MRI is significantly associated with a poor surgical outcome and a considerable factor for the proper surgical indication.

• Progress in Medical Physics
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• v.10 no.1
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• pp.23-32
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• 1999

Combined MRI and Relaxogram approach was introduced as a very useful tool for fat study. The phantoms simulating homogeneous mixture of fat and non-fat environments were measured with spin echo pulse sequence on a 0.15 T whole body imager. From 45 scans, the Tl values were obtained by fitting the data to continuous distribution (CONTIN) of relaxation time. This relaxogram gives broad distributions of relaxation time, which are characterized by a number of peaks with characteristic T1 values. Two distinct peaks in relaxogram were observed and identified as signals from com oil and gelatin gel. This model system can be served as simulating the distribution of fat in muscle. Also the relative ratio of two components, which is proportional to the area under the peak, is estimated and compared to nominal values. Based on the good agreement between two predictions, the values from our proposed method agreed with nominal values within $\pm$7 % error. The effects of different concentration of contrast agent and different region of interest are presented. To optimize total scan times, the minimum required data points and so further reduction in total scan times are discussed.