• 한국연소학회:학술대회논문집
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• 한국연소학회 2006년도 제32회 KOSCO SYMPOSIUM 논문집
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• pp.137-143
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• 2006

The effect of electric fields on flame speed has been investigated experimentally by observing propagating premixed flames in a tube for methane/air mixtures. The flame speeds were measured in both the normal and micro gravity conditions to substantiate the measurements. The results show that the flame speeds were enhanced by both the AC and DC electric fields, as the flame approached to the high voltage electrode located on the one end of the tube. The enhancement of flame speed was proportional to the square root of the electric field intensity, defined as the voltage applied divided by the distance of flame from the high voltage electrode, when the electric field intensity is sufficiently large. When the electric field intensity was low, there existed critical intensities, below which the electric fields did not influence the flame speed. This critical electric field intensity correlated well with the flame speed.

• 한국소음진동공학회논문집
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• 제17권1호
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• pp.3-9
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• 2007

In this paper, a numerical case study is carried out on the hydroelastic vibration of rectangular plate with various fluid field. It is assumed that the tank wall is clamped along the plate edges. The VMM(virtual mass method) of Nastran is used for the simulation of fluid domain and calculating natural frequency of fluid-coupled structure. In this paper, natural frequencies are calculated and compared for rectangular plates with various fluid field such as infinite fluid and finite fluid, length change of finite fluid field and various fluid contacting conditions.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집
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• pp.601-604
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• 2001

The insulation materials of cables used for underground power transmission requires a higher insulating capability, and the most popular method to examine the cable is partial discharge test due to applying variation voltage. In the thesis, air void, silicone oil, of which may possibly exist real cables, are simulated by Electro 2D program. Also the relations between calculated field strength and the void defect type in the cable joint materials. In the modeling, eclectic field inner to the cable joint material composed by XLPE and EPDM is modeling simulated. We obtained the electric field distribution in void due to two conditions.

• Applied Microscopy
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• 제46권4호
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• pp.227-237
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• 2016

This investigation deals with the process of field electron emission from composite microemitters. Tested emitters consisted of a tungsten or carbon-fiber core, coated with a dielectric material. Two coating materials were used: (1) Clark Electromedical Instruments Epoxylite resin and (2) Epidian 6 Epoxy resin (based on bisphenol A). Various properties of these emitters were measured, including the current-voltage characteristics, which are presented as Fowler-Nordheim plots, and the corresponding electron emission images. A field electron microscope with a tip (cathode) to screen (anode) distance of 10 mm was used to electrically characterize the emitters. Measurements were carried out under ultra-high vacuum conditions with a base pressure of $10^{-6}$ Pascal ($10^{-8}$ mbar).

• 드라이브 ㆍ 컨트롤
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• 제11권3호
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• pp.22-30
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• 2014

In this research, the energy stability level method is used for examining the stable state of Field Robot under effects of swing motion, at particular postures of manipulator, and terrain conditions. The energy stability level is calculated by using the dynamic models of Field Robot, subjected to the concept of equilibrium plane and support boundary. The results, simulated by using computing program for estimating the potential overturning of Field Robot, supply useful predictions of stability analysis for designers and operators.

• 한국환경농학회지
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• 제39권1호
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• pp.75-82
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• 2020

본 연구에서는 시설재배 하는 브로콜리 중 indoxacarb 및 pymetrozine의 경시적 잔류변화를 조사하여 생물학적 반감기와 감소상수를 산출하여 생산단계 잔류허용기준(PHRL)을 설정하고자 하였다. 포장시험은 충주시(포장 1) 및 군산시(포장 2)에 소재한 시설재배지에서 수행되었으며 약제살포 후 0, 1, 2, 3, 5, 7, 10일차에 시료를 채취하여 분석하였다. 브로콜리 중 잔류량은 HPLC-DAD로 분석하였으며, indoxacarb 및 pymetrozine의 회수율은 각각 94.3~105.4% 및 81.8~96.0%이었으며, MLOQ (Method Limit of quantitation)는 모두 0.05 mg/kg이었다. 브로콜리 중 indoxacarb 및 pymetrozine의 생물학적 반감기는 각각 2.9일, 3.2~3.8일이었으며, 감소상수의 95% 신뢰수준 하한치는 indoxacarb 0.1508 및 0.2017, pymetrozine 0.1489 및 0.1577로써 포장별, 약제별 유의적 차이(p<0.05)가 없었다. 브로콜리 중 농약 잔류량 소실특성의 주요 요인은 증체로 인한 희석효과이었으며, 브로콜리의 수확 10일전 PHRL은 indoxacarb의 경우 30.06(포장 1) 및 18.07(포장 2) mg/kg이었고, pymetrozine은 4.84(포장 1) 및 4.43(포장 2) mg/kg이었다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2005년도 춘계 학술발표회 논문집
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• pp.217-224
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• 2005

A higher order zig-zag shell theory is developed to refine the predictions of the mechanical and thermal behaviors partially coupled. The in-plane displacement fields are constructed by superimposing linear zig-zag field to the smooth globally cubic varying field through the thickness. Smooth parabolic distribution through the thickness is assumed in the out-of-plane displacement in order to consider transverse normal deformation and stress. The layer-dependent degrees of freedom of displacement fields are expressed in terms of reference primary degrees of freedom by applying interface continuity conditions as well as bounding surface conditions of transverse shear stresses. Thus the proposed theory has only seven primary unknowns and they do not depend upon the number of layers. In the description of geometry and deformation of shell surface, all rigorous exact expressions are used. Through the numerical examples of partially coupled analysis, the accuracy and efficiency of the present theory are demonstrated. The present theory is suitable in the predictions of deformation and stresses of thick composite shell under mechanical and thermal loads combined.

• The Korean Journal of Ecology
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• 제6권4호
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• pp.250-256
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• 1983

Dehiscence of ginseng seeds under the various conditions, growing experiment in the different soil conditions, and growing experiment with extracts obtained by water passed the pot of 4 year ginseng plants were performed. The results obtained are as follows: The survival rate of ginseng plants in the soil of ginseng field sterilized by MIYAZAWA's method was higher than that of the non-sterilized, but lower than that of the control. The survival rate of ginseng plants on the sterilized soil of ginseng field was lower than that on the surrounding soil. The growth of ginseng plants cultivated with the water passed through the pot-planted 4-year-old ginseng plants was strongly inhibited in comparison with the control. Besides biological cause, chemical products excreted from the root of ginseng plants might be the important factors of soil sickness in the successive cultivation of the same plants.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1494-1498
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• 2004

Transition sequence of rocket to ramjet was simulated numerically for a two-dimensional axisymmetric can-type ramjet engine. Multi-species preconditioned Navier-Stokes equations with $k-{\varepsilon}$ turbulence model and finite-rate chemistry model was employed. To calculate transition sequence, initial flow-field conditions for inlet diffuser with closed port-cover was computed first, and then that result was applied as initial conditions after port-cover opened. Terminal shock was developed as a result of increased pressure in a combustor due to combustion and ramjet operated at supercritical condition. For a smaller nozzle throat area, buzz instability was occurred. Strong pressure oscillations were observed as a result of forward and backward movement of terminal shock and those oscillations were not damped out.

• 응용통계연구
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• 제10권1호
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• pp.15-27
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• 1997

Randomized block design (RBD) with three replication is very frequently adopted in agricultural experiments of the Rural Development Administration of Korea. Even though it works well in field trials of traditional crops, it may not accomodate trial site conditions and/or experimental environment. In this research report, we deal with two such cases. The first case is for a crop experiment in green houses. In house conditions, RBD may not be appropriate since it cannot reflect two directions of the yield gradient. So, a Latin square design is suggested as an alternative. The second case is for local field experiments of the newly-inbred rice. RBD with three replications is used without doubt for decades, even though the site layout is not appropriately shaped for the design. In this case, we suggest the RBD in two blocks with multiple replicates for control varieties as an alternative. To improve the quality of statistical experimental designs in over one-thousand agricultural trials performed annually in the Rural Development Administration, we need to re-train agricultural researchers on the design and analysis of experiments and call for concerns of Korean statisticians.