• 대한기계학회논문집
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• 제18권2호
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• pp.251-259
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• 1994

Nearfield acoustic holography is known as a powerful tool to study sound radiation from a structure. In this work, the so called backward propagation of sound pressure field is studied to obtain the structure velocity distribution. The results, which were obtained using FFT algorithms, are presented for a finite plate excited at the frequencies above and below coincidence. These results illustrate the effect of stand-off distance and noise. An optimum cutoff frequency in wavenumber domain was suggested to reduce the effects of evanescent wave in the backward propagation. The experimental results were also included for a plate to demonstrate the effectiveness of the suggested cutoff frequency. The optimum cutoff frequency to exclude the unwanted noise in the process of reconstruction of the velocity field gives the good results in both simulations and experiments.

• 한국기계가공학회지
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• 제8권4호
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• pp.14-19
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• 2009

Micro fluid channels are machined on quartz glass using powder blasting, and the machining characteristics of the channels are experimentally evaluated. The powder blasting process parameters such as injection pressure, abrasive particle size and density, stand-off distance, number of nozzle scanning, and shape/size of the required patterns affect machining results. In this study, the influence of the number of nozzle scanning, abrasive particle size, and blasting pressure on the formation of micro channels is investigated. Machined shapes and surface roughness are measured, and the results are discussed. Through the experiments and analysis, LOC are ettectinely machined on quartz glass using powder blasting.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.304-308
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• 2002

This paper studies stand-alone photovoltaic array for solar lighting lamp. The solar lighting lamp has PV modules, batteries. and charge & discharge system. The charge efficiency is improved for the control of each battery which is divided the charge from the discharge to change the structure of existing solar lighting lamp charge & discharge system. so, the charge and discharge times are reduced of 50%. and the depth of discharge control can be controlled in the discharge cut off voltage. This can be effective of battery use. If a battery is out of order, this system can be executed for a regular period. so we saved the repair cost and developed of system's stabilization. It is possible economical effect to apply for solar lighting lamp used photovoltaic array.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2011년도 정기 학술대회
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• pp.152-155
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• 2011

최근 폭발 등 극한하중에 대한 관심의 증대와 함께 방폭 및 연쇄붕괴방지를 위한 연구가 활발히 진행되고 있다. 이에, 본 연구에서는 폭발하중하의 강구조물의 손상도와 저항성능을 수치적으로 평가하고자 하였다. 이를 위해 구조물의 폭발피해경감을 위해 가장 중요한 구조부재인 기둥을 대상으로 폭발물과 구조물과의 이격거리를 달리하여 폭발하중을 적용하였다. 유한요소해석을 수행한 결과를 토대로 기둥의 손상도와 잔여압축강도를 비교하고 관계를 도출하였다. 본 연구의 목적은 폭발에 의해 기둥이 손상된 경우 구조물 전체의 연쇄붕괴저항성능에의 손상된 기둥의 기여도를 평가하는 것이다.

• 전자공학회논문지B
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• 제31B권8호
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• pp.172-180
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• 1994

Implantable biotelemetry systems are indispensable tools not only in animal research but also in clinical medicine as such systems enable the acquisition of otherwise unavailable physiological data. We present the manufacture of CMOS IC and its system for implantable multichannel biotelemeter system. The internal circuits of this system are designed not only to achieve as multiple functions and low power dissipation as possible but also to enable continuous measurement of physiological data. Its main functions are to enable continuous measurement of physiological data and to accomplish on-off power swiching of an implantable battery by receiving appropriate commanc signals from an external circuit. The implantable circuits of this system are designed and fabricated on a single silicon chip using $1.5\mu$m n-well CMOS process technology. The total power dissipation of implantable circuits for a continuous operation was 6.7mW and for a stand-by operation was 15.2$\mu$ W. This system used together with approriate sensors is expected to contribute to clinical medicine telemetry system of measuring and wireless transmitting such significant physiological parameters as pressure pH and temperature.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2002년도 추계종합학술대회
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• pp.192-195
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• 2002

21세기 신산업의 발전은 생활의 편리함과 인류발전의 제2의 도약 기틀을 마련함으로 제2의 산업혁명이라 불리운다. 특히 지속적이고 급속도로 발전하고 있는 정보통신산업은 일상생활의 일부분이 되고 있고 응용범위를 넓혀갈 것이다. 이에 상대적으로 소외되었고, 발전진화가 더딘 어업통신의 현황을 고찰하고, 향후 연근해 지역에 적합한 어선통신의 개선방안을 제시하였다.

• 약학회지
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• 제2권1_2호
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• pp.1-8
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• 1953

The leaves of prunus padus L. var. Seoulensis Nakai distributed widely in Korea, were extracted with boiling alcohol(95%) after being mixed with calcium carbonate. The aqueous solution distilled off alcohol from the above filtered extract under the reduced pressure was evaporated to the dryness. The residue was extracted with acetic ether on the water-bath and the acetic ether solution extract was allowed to stand for a weck after removing out of acetic ether almostly, then a colorless necdles were Crystalized out which has the following characteristics : $C_{14}$ $H_{17}$ $O_{6}$ N, began to melt at 138-139.deg. bitter taste [.alpha.]$_$ $D^{20}$ ]=-26.99.deg. soluble in water, alcohol acetone acetic ether etc. slightly soluble in chloroform. It was proved to be identical with prunasine due to above characteristics and determination of Benzal-dehyde HCN and glucose respectively which was obtained on hydrolysis of this glycoside with emulsine.

• 한국연소학회지
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• 제1권2호
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• pp.41-49
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• 1996

A numerical study is conducted to investigate the periodically unstable shock induced combustion around blunt bodies in stoichiometric hydrogen-air mixtures. Euler equations are spatially discretized by upwind-biased third order scheme and temporally integrated by Runge-Kutta method. Chemistry model used in this study involves 8 elementary kinetics steps and 7 species. At a constant Mach number, the effects of projectile size, inflow pressure and inflow temperature are examined with Lehr#s experimental condition as a reference. In addition to oscillation frequency, characteristic distances and time averaged values are found from the result to find an relation with dimensionless parameters. As a result, it is found that the effects of inflow pressure and body size are very similar and $Damk{\ddot{o}}hler$ number plays an important role in determining the instability characteristics.

• International Journal of Aeronautical and Space Sciences
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• 제18권3호
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• pp.425-435
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• 2017

In this work, an overview of flow diagnosis in a shock tunnel is made by means of using established techniques that are easy to setup, economical to arrange, and simple to measure. One flow condition was considered having Mach number of 6 at the nozzle-exit, regarded as freestream. Measured aerothermodynamic data such as shock wave speed, wall static and total pressures, surface heat flux, and shock stand-off distance ahead of test model showed good agreement with calculation. This study shows an overall procedure of flow diagnosis in a shock tunnel in a single manuscript. Outcomes are thought to be useful in the field of education and also in a preliminary stage of high-speed vehicle design and tests, that need to be performed within a short time with decent accuracy.

• Journal of Contemporary Eastern Asia
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• 제20권2호
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• pp.197-209
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• 2021

This article deals with the asymmetrical relations between Australia and China and explores their interdependence, tensions, and societal outlooks. Both countries are dependent on one another for trade to different degrees but attempt to diversify their supply chains. While there is no united position on China in Australia, there has been a bipartisan support for the counter-interference legislation there. The newly established security pact of the United States (US), the United Kingdom (UK) and Australia - 'AUKUS' - has brought a new dimension into these tensions and will most likely lead to an arms race. The author explores how a so-called middle power such as Australia balances the related economic and strategic interests and priorities. Although Australia has been vulnerable in its asymmetric relationship with China, it has shown that it is not a passive and helpless actor when facing an economic coercion. The interdependence has become a moderating factor in this strategic stand-off. Additionally, Australia demonstrates its tendency to reinforce its traditional reliance on its previous more powerful allies, the UK and the US.