• 한국결정성장학회지
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• 제24권2호
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• pp.59-64
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• 2014

전해질로 $Na_2SiO_3$을 사용하여 A1050 알루미늄 판재를 pulse 폭 $ 2000{\mu}sec$, impulse 420 V, 400 ${\mu}$sec의 unipolar pulse로 플라즈마 전해 산화 코팅(plasma electrolytic oxidation coating)을 하여 산화 피막을 2, 5, 15, 30분에 따라 형성시킨 다음 산화피막을 분석하였다. 표면에 형성된 산화물의 결정상은 ${\alpha}-alumina$와 ${\gamma}-Alumina$로서 시간에 따른 변화는 없었다. 반응 초반에는 ${\gamma}-Alumina$가 많이 생성되었지만 시간이 갈수록 ${\gamma}-Alumina$의 양에는 변화 없이 ${\alpha}-alumina$가 많이 생겨남을 알 수 있었다. 이런 결과는 micro plasma에 의해서 ${\gamma}-Alumina$가 우선 생성되고, 이후 계속되는 micro plasma의 열에 의해서 ${\alpha}-alumina$로의 전이가 일어나기 때문으로 판단된다.

• 한국인쇄학회지
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• 제30권1호
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• pp.21-33
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• 2012

This research attempts to analyze the effect of printed-saving coupons distributed by major discount store on consumer purchasing intention. Those consumers having used printed-saving coupon in major discount store in Daejeon were selected as respondents. 121 copies were retreated from 150 questionnaires. For data analysis, frequency analysis for respondents' characteristics, Cronbach's alpha for reliability of analysis, and $X^2$ test of multi-regression analysis for testing hypothesis were utilized. The result of analysis shows 1) the way of using coupon is respectively different according to sex, age group, marital status, term of coupon, and the number of using coupon; 2) Attributes of coupon partially influence on purchasing intention of consumers. Only shopping cost cutting is insignificant, while keeping convenience, impulse buying, scheduled purchasing are significant. The most effective variable is scheduled purchasing, keeping convenience, and impulse buying influence on purchasing intension of consumers. Therefore, offering printed-coupon by major discount store is useful tool to induce consumers to planned purchasing.

• 한국초전도ㆍ저온공학회논문지
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• 제5권3호
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• pp.48-51
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• 2003

HTS power transmission cable is expected to transport large electric power with a compact size. We are developing a 3-core, 22.9 kV, 50 MVA class HTS power cable, and each core consists of a conductor and shield wound with Bi-2223 tapes, electrical insulation with laminated polypropylene paper (LPP) impregnated with liquid nitrogen. This paper describes the design and experimental results of the model cable for the 22.9 kV, 50 MVA class HTS power transmission cable. The model cable was used the SUS tapes instead of HTS tapes because of testing the electrical characteristics only. The model cable was 1.3 m long and electrical insulation thickness was 4.5 mm. The model cable was evaluated the partial discharge (PD), AC and Impulse withstand voltage in liquid nitrogen. The AC and Impulse withstands voltage and PD inception stress was satisfied with the standard of Korea Electric Power Corporation (KEPCO) in the test results. The 3-core 22.9 kV, 50 MVA class HTS power cable has been designed and manufactured based on these experimental results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.868-869
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• 2011

Domestic Foreign automaker's are focused on the high-efficiency, low emission cars development. On the way, the hybrid car is the first priority. Hybrid electric vehicle battery pack configurations, EV Relay one of the key components of the engine driving, to assist in the drive motor to supply electrical energy to the battery is a device for opening and closing of the output device. EV Relay determine the longevity and the replacement cycle, The EV Relay environmental conditions and duty cycle considering the reliability tests are essential requirements of many automotive companies to respond to RFQ, this test is essential. This paper using Maxwell Software for Prediction of the Ev Relay impulse, the theoretical data to obtain the impulse to develop methods for mechanical testing after to take advantage of it.

• 한국세라믹학회지
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• 제47권6호
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• pp.491-497
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• 2010

In this paper, we employed the classical molecular dynamics simulations using Tersoff's potential to calculate the elastic constants of the silicon carbide (SiC) crystal at high temperature. The elastic constants of the SiC crystal were calculated based on the stress-strain characteristics, which were drawn by the simulation using LAMMPS software. At the same time, the elastic constants of the SiC ceramics were measured at different temperatures by impulse excitation testing (IET) method. Based on the simulated stress-strain results, the SiC crystal showed the elastic deformation characteristics at the low temperature region, while a slight plastic deformation behavior was observed at high strain over $1,000^{\circ}C$ temperature. The elastic constants of the SiC crystal were changed from about 475 GPa to 425 GPa by increasing the temperature from RT to $1,250^{\circ}C$. When compared to the experimental values of the SiC ceramics, the simulation results, which are unable to obtain by experiments, are found to be very useful to predict the stress-strain behaviors and the elastic constant of the ceramics at high temperature.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 춘계학술대회 논문집 반도체 재료 센서 박막재료 전자세라믹스
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• pp.179-182
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• 2004

ZnO varistor for transmission class arrester$({\Phi}65{\times}20mm)$ of 10kA(Class 3) grade was recently developed in korea and is tested for the properties by switching surge operating duty test to know the line discharge class and complex surge property in electric properties. To find out changing rate of residual voltage before and after lightning impulse residual voltage testing, the sample is cool to room temperature after finishing switching surge operating duty test, and the rate is good as 1.0~1.7%. The element had been considered as applicable ZnO varistor for electricity transmission from the test results of state conterl, switching surge operating duty, thermal stability and above test. But various test should be required for actual application because this is a part of the to be needed for application.

• Communications for Statistical Applications and Methods
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• 제17권2호
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• pp.241-253
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• 2010

표준 단위근 검정이 실제 시계열자료의 단위근 귀무가설을 기각하지 못하는 경우가 많아지고 검정력에 문제점을 드러내면서 이와는 반대로 정상성 귀무가설을 단위근 대립가설에 대해 검정하는 방안이 제기되어 왔다. 본 연구는 국내 광역지역의 주택가격 시계열자료에 귀무가설과 대립가설이 바뀐 두 가지 종류의 단위근 검정법을 모두 적용시켜 보았다. 그리고 지역 자료간 통계적 역학관계를 검정하기 위한 인과관계, 교차상관관계 또 충격반응 및 분산분해 등에 대한 분석 결과는 대체로 일관된 성향을 보이는 것으로 나타났다.

• 대한의용생체공학회:의공학회지
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• 제27권5호
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• pp.229-236
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• 2006

The acoustic field analysis method is the superior calibration method for rectifying the ultrasonic probe sensitivity. This method also can be applied to evaluate the probe performance in clinical fields without numerical analysis and precise measurements. In this paper, we propose the method of acoustic field pattern analysis with probe channel division for the evaluation of diagnostic ultrasound probe characterization. In order to verify our purpose, we performed a set of experiments. We measured the acoustic-field pattern of the three inferiority probes by channel division to evaluate an acoustic field distribution and impulse response characteristics. By comparing the results of acoustic field measurement method with that of conventional method such as impulse response and live image test for linear array probes, it is demonstrated that the ultrasound field measurement method is more effective then conventional method in detection of defective elements.

• Smart Structures and Systems
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• 제4권1호
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• pp.1-17
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• 2008

This study proposes a conceptual framework of in-situ vibration tests and analyses for quality appraisal of non-slender, cast-in-place piles with irregular cross-section configuration. It evaluates a frequency index from vibration recordings to a series of impulse loadings that is related to total soil-resistance forces around a pile, so as to assess if the pile achieves the design requirement in terms of bearing capacity. In particular, in-situ pile-vibration tests in sequential are carried out, in which dropping a weight from different heights generates series impulse loadings with low-to-high amplitudes. The high-amplitude impulse is designed in way that the load will generate equivalent static load that is equal to or larger than the designed bearing capacity of the pile. This study then uses empirical mode decomposition and Hilbert spectral analysis for processing the nonstationary, short-period recordings, so as to single out with accuracy the frequency index. Comparison of the frequency indices identified from the recordings to the series loadings with the design-based one would tell if the total soil resistance force remains linear or nonlinear and subsequently for the quality appraisal of the pile. As an example, this study investigates six data sets collected from the in-situ tests of two piles in Taipu water pump project, Jiangshu Province of China. It concludes that the two piles have the actual axial load capacity higher than the designed bearing capacity. The true bearing capacity of the piles under investigation can be estimated with accuracy if the amplitude of impact loadings is further increased and the analyses are calibrated with the static testing results.

• Tuberculosis and Respiratory Diseases
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• 제85권2호
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• pp.175-184
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• 2022

Background: Post-tuberculosis (TB) sequelae is a commonly encountered clinical entity, especially in high TB burden countries. This may represent chronic anatomic sequelae of previously treated TB, with frequent symptomatic presentation. This pilot study was aimed to investigate the pulmonary functions and systemic inflammatory markers in patients with post-TB sequelae (PTBS) and to compare them with post-TB without sequelae (PTBWS) participants and healthy controls. Methods: A total of 30 participants were enrolled, PTBS (n=10), PTBWS (n=10), and healthy controls (n=10). Pulmonary function tests included spirometry and measurement of airway impedance by impulse oscillometry. Serum levels of matrix metalloproteinase (MMP)-1, transforming growth factor-β, and interferon-γ were estimated. Results: Slow vital capacity (SVC), forced vital capacity (FVC), forced expiratory volume in 1 second (FEV₁), FEV₁/FVC, and peak expiratory flow were significantly lower in PTBS as compared to controls. SVC and FEV₁ were significantly less in PTBS as compared to PTBWS. Total airway impedance (Z₅), total airway resistance (R₅), central airway resistance (R₂₀), area of reactance (Ax), and resonant frequency (Fres) were significantly higher and respiratory reactance at 5 and 20 Hz (X₅, X₂₀) were significantly lower in PTBS as compared to PTBWS. Spirometry parameters correlated with impulse oscillometry parameters in PTBS. Serum MMP-1 level was significantly higher in PTBS as compared to other groups. Conclusion: Significant pulmonary function impairment was observed in PTBS, and raised serum MMP-1 levels compared with PTBWS and healthy controls. Follow-up pulmonary function testing is recommended after treatment of TB for early diagnosis and treatment of PTBS.