• Structural Engineering and Mechanics
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• 제55권2호
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• pp.435-459
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• 2015

Parametric resonance of shear deformable composite skew plates subjected to non-uniform (parabolic) and linearly varying periodic edge loading is studied for different boundary conditions. The skew plate structural model is based on higher order shear deformation theory (HSDT), which accurately predicts the numerical results for thick skew plate. The total energy functional is derived for the skew plates from total potential energy and kinetic energy of the plate. The strain energy which is the part of total potential energy contains membrane energy, bending energy, additional bending energy due to additional change in curvature and shear energy due to shear deformation, respectively. The total energy functional is solved using Rayleigh-Ritz method in conjunction with boundary characteristics orthonormal polynomials (BCOPs) functions. The orthonormal polynomials are generated for unit square domain using Gram-Schmidt orthogonalization process. Bolotin method is followed to obtain the boundaries of parametric resonance region with higher order approximation. These boundaries are traced by the periodic solution of Mathieu-Hill equations with period T and 2T. Effect of various parameters like skew angle, span-to-thickness ratio, aspect ratio, boundary conditions, static load factor on parametric resonance of skew plate have been investigated. The investigation also includes influence of different types of linearly varying loading and parabolically varying bi-axial loading.

• 천문학논총
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• 제30권2호
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• pp.193-195
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• 2015

The Palomar Transient Factory is a project making use of a Schmidt 48 inch telescope located on the Palomar Mountain, which is surveying the sky with dynamical cadences. It was deployed in 2009 and the observed sky region is over 1200 square degrees. We have studied the long-term periodic variabilities of the known galactic cataclysmic variables (CVs). More than 20 of the sources had been found to have long term periodic signals, ranging from several tens of days to several hundreds of days. Some possible scenarios are proposed to explain the results, such as a magnetic field change of the companion star, precession of the accretion disk, triple systems and superoutburst cycles. Some preliminary discussion will be presented in this article.

• 복식
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• 제32권
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• pp.21-30
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• 1997

Chogori the basic upper garment of korea costume occupies an important role in tra-ditional dressing and continues to be in use to the present days. Of course there has been changes in the length and line of Chogori with the flow of time based on the Ancient Yoo. This is a study of the 14 parts of Chgori based on statistical analysis by computing the practical measuements. Here the statistical analysis is a objective and quantitative of the stylistic changes in Chogori with time. In this study from the data the Mean and Standard deviation has been evaluated and periodic change is shown by graph to test the periodic change T-test Regressional analysis Index analysis has been used. The results are as follows: 1. The length of clothing has changed with time except the sleeve length. Here the length of clothing means all the other measurements ex-cept the sleeve Thus while the measurements of sleeve length has been uniquely unchanged the other measurements have influenced each other. 2. Generally the form of Chogori had the tendency towards smallness in the 19th cen-tury. But it tended to get larger in the 20th century. 3. Compared to other periods the mode of 19th and 20th century Chogori was widely ac-cepted as the Standard deviation of that period was very narrow. 4. The results seen from the regressional analysis of the Cho-sun period woman's Chogori satisfy the t-value and R-squared and thus support the regression formula presump-tion. 5. From the index analysis it is revealed that with decrease in the armhole measurement sleeve measurement and neckband; relatively same decrease in the wrist measurement; and very marked decrease in the sideline measurement.

• 한국정보과학회논문지:정보통신
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• 제32권3호
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• pp.339-349
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• 2005

최근 수년 동안, 데이타 방송기술은 많은 수의 클라이언트를 갖는 이동 컴퓨팅 환경에서 매우 효과적인 데이타 전달 시스템으로 주목받고 있다. 특히 흔성 방송은 주기적인 반복 데이타 방송과 온디멘드 방송을 통해, 제한된 대역폭 상에서 많은 이동 클라이언트를 수용하면서 동시에 동적인 데이타 액세스를 지원할 수 있다. 그러나 기존의 흔성 방송 알고리즘에서 데이타 액세스 변화를 파악하기 위해 사용하는 기법에는 문제가 있다. 즉, 많은 요청을 받은 데이타 아이템을 반복 방송에 추가시키면 액세스 요구가 적어져 이 데이타 아이템이 방송되고 있기 때문에 요청이 적어진 것인지 아니면 수요가 줄어서 요청이 적어진 것인지 모른다는 것이다. 기존 연구에서는 이 문제 때문에 냉각값을 곱해 서서히 제거하는 방법을 사용하거나 일부러 방송에서 누락시켜 수요를 창출하는 방법을 사용한다. 그러나 이 두 방법은 모두 데이타의 특성을 고려하지 않는 인공적인 기법이다. 본 논문에서 이러한 문제를 해결하기 위해 데이타 유형을 분류하여 방송하는 데이타 방송 알고리즘 RTAHB-DT(Real-Time Adaptive Hybrid Broadcasting based on Data Type)를 제안하고, 시뮬레이션을 사용해 제안 알고리즘의 성능을 분석한다.

• 환경생물
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• 제22권3호
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• pp.387-393
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• 2004

사료를 통한 benzo(a)pyrene이 조피볼락, Sebastes schlegeli의 lipid peroxidation (LPO), superoxide dismutase(SOD)활성과 간 조직의 병변 현상에 미치는 영향을 연구하기위해 0 (대조구), 0.5, 1.0, 1.5, 2.0 mg $kg^{-1}$ 농도의 사료를 조제하여 30일간 급이하였다. LPO는 2.0mg kg$^{-1}$농도구에서 전 실험기간 동안 유의적으로 증가하였고, SOD 활성도 2.0 mg $kg^{-1}$ 농도구에서 30일째에 유의적으로 증가하였다. 간 조직 검경시 10일째에 1.0mg $kg^{-1}$ 이상의 농도구에서 세포비대가 나타났고, 같은 농도에서 periodic acid-Schiff (PAS) 염색시 양성으로 나타나는 granule이 30일째에 나타났고, 2.0mg $kg^{-1}$ 농도구에서는 20일째부터 관찰되었다. 그리고, 30일째 2.0mg $kg^{-1}$ 농도구의 일부 어체에서는 간 세포의 괴사가 관찰되었다.

• Journal of electromagnetic engineering and science
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• 제12권1호
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• pp.37-44
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• 2012

This paper describes a compact and novel wireless vital sign sensor at 2.4 GHz that can detect heartbeat and respiration signals. The oscillator circuit incorporates a planar resonator, which functions as a series feedback element as well as a near-field radiator. The periodic movement of a human body during aerobic exercise could cause an input impedance variation of the radiator within near-field range. This variation results in a corresponding change in the oscillation frequency and this change has been utilized for the sensing of human vital signs. In addition, a surface acoustic wave (SAW) filter and power detector have been used to increase the system sensitivity and to transform the frequency variation into a voltage waveform. The experimental results show that the proposed sensor placed 20 mm away from a human body can detect the vital signs very accurately.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1617-1622
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• 2008

We report a new molecular detection process which measures the changes in the plasmon resonance peaks of periodic Au nanoparticle arrays fabricated using the electron beam lithography. As the Au nanoparticle arrays are modified by the chemical reaction in solutions having various concentrations of a target molecule, both the position and intensity of the plasmon peak change in proportion to the concentration of the target molecule. We expect that the process developed in this work can be employed for fine tuning of the plasmon peak wavelength and also for the optical detection of various kinds of molecules. Moreover, this method may improve the measurement accuracy compared with existing approaches that use only one change (peak wavelength or peak intensity) as a readout value for the molecular detection.

• 소성∙가공
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• 제5권4호
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• pp.327-336
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• 1996

The effect of dynamic strain aging on high temperature deformation behaviour of the A-Mg alloy was investigated by strain rate change tests and stress relaxation tests between 20$0^{\circ}C$and 50$0^{\circ}C$. Yield point, short stress transient and periodic discontinuities on the stress-strain curve were considered as an evidence of the effect of dynamic strain aging. With this criterion two distinct strain rate-temperature regimes could be manifested. Dynamic strain aging was considered to be effective in the high temperature-low strain rate regime, whereas dynamic recovery was a dominant deformation mechanism in the low temperature-high strain rate regime. It was found that dynamic strain aging in the high temperature deformation was governed by the mechcanism of diffusion-controlled, viscous dislocation movement.

• 한국정보기술학회 영문논문지
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• 제10권1호
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• pp.57-69
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• 2020

In general, many IoT devices, including smart phones, use LTE, Wi-Fi, and Bluetooth, and these communication modules generate a lot of energy consumption during periodic data transmission. This paper proposes a method of the data transmission mode change for improving energy efficiency in various communication environments that mobile devices may encounter. We propose an algorithm for setting the mode considering energy efficiency, data transmission performance and cost when the mobile device transmits data, and transmitting the data in an optimized manner according to the state of the mobile device. The proposed algorithm is implemented through experiments on energy efficiency for each communication module, and the scenario is used to verify how efficiently the proposed algorithm uses energy.

• 한국산업보건학회지
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• 제33권3호
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• pp.280-283
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• 2023

Objectives: The purpose of this study was to examine the change in exposure concentration in the cleaning process after installing a local exhaust system. Methods: Dichloromethane measurement was conducted according to the KOSHA Guide (A-19-2019). Results: After the local exhaust device was installed, a total of three measurements were conducted, including temporary work environment measurements, and all of the measurements did not exceed the DCM exposure standard, but were more than 50% of the DCM Time Weighted Average((8-TWA) Conclusions: It is thought that the local ventilation system of a small business needs not only support for the initial installation cost, but also educational support for maintaining the performance of the local ventilation system and support for consumables (adsorbents, filters, etc.) that incur periodic costs.