• 동력기계공학회지
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• 제4권4호
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• pp.41-47
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• 2000

Fatigue crack propagation rate and threshold characteristics of the SA516/70 steel which is used for the low temperature pressure vessels, were studied in the room temperature of $25^{\circ}C$ and low temperature ranges of $-10^{\circ}C,\;-30^{\circ}C,\;-60^{\circ}C\;and\;-80^{\circ}C$ with stress ratio of R=0.1. In the logarithmic relationship between the fatigue crack propagation rate($d{\alpha}/dN$) and stress intensity factor range ${\Delta}K$, the linear relationship was obtained up to $d{\alpha}/dN=4.425{\times}10^4mm/cycle$ in the same of room temperature, but in low temperature case, the relationship was extended to the range of low crack propagation rate. The fractured specimens were examined by SEM. Tested results showed that specimen failed at low temperature exhibit the quasi-cleavage fracture formation however considerable ductility proceed final fracture.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.I
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• pp.793-796
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• 2005

A structure and a design of device were developed to fabricate large-scale active matrix organic light-emitting diode (AMOLED) display with good color purity and high aperture ratio. With these technologies, we developed a full color 14.1 inch WXGA AMOLED display. For the integration of OLED on an active matrix a-Si TFT backplane, an efficient top emission OLED is essential since the TFT circuitry covers a large position of the pixel aperture. These technologies will enable up the OLED applications to larger size displays such as desktop monitors and TVs.

• 한국지반신소재학회논문집
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• 제11권2호
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• pp.11-20
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• 2012

미관통 SCP공법은 개량 대상지반인 연약점토층 밑에 존재하는 지지층까지 모래말뚝을 관통시키지 않고 미관통 상태 그대로 SCP를 지반 중에 조성하는 공법으로 본 연구에서는 저치환율인 경우 압밀도에 따른 미관통 SCP공법과 관통 SCP 공법을 병용한 복합지반의 압밀침하 거동을 수치해석을 통해 비교 하였다. 본 연구결과 관통 SCP지반의 침하특성은 압밀도에 상관없이 거의 일정하나 미관통 SCP지반의 침하특성은 압밀도가 감소하고 관통율($H_d/H$)이 감소할수록 상부점토지반의 침하량이 더 크게 증가되었다. 또한 미관통 SCP의 하단부에는 응력집중효과가 발휘되지 않았으며 응력분담비는 압밀도에 관계없이 거의 일정한 양상을 보였다.

• The Korean Journal of Ecology
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• 제19권1호
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• pp.71-80
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• 1996

The effects of simulated acid rain on the growth and interspecific competition of Echinochloa crus-galli and Digitaria sanguinalis were studied. Changes of growth in height and dry weight were examined and competition between the two species was investigated using the experimental model proposed by de Wit (1960). The experiments were carried out in the greenhouse, and test plants were germinated and grown for 4 weeks and then sprayed with simulated acid rain of pH 5.6, 4.2 and 2.8 for another 8 weeks. In de Wit replacement experiments, the variation of density and the treatment of simulated acid rain showed little effect on the interspecific competition between E. Crus-galli and D.sanguinalis. The ratio diagram, another method to reveal the interrelations between two competing species, always showed the predominance of E. crus-galli in competition, regardless of density and pH. The interspecific competition of the two species, represented by relative yield total (RYT), revealed that intraspecific competition was stronger than interspecific competition in both species.The treatment of simulated acid rain showed little effect on the growth of E. Crus-galli and D. sanguinalis. Height growth of both species did not differ from that of control (pH 5.6), but root/shoot ratio increased with the decrease in pH of simulated acid rain. Growth of tatal dry weight of E. crus-galli and D. sanguinalis was not influenced by the change of pH, except that D.sanguinalis showed a decrease in the total dry weight at pH 2.8 along with a visible sign of white spots on leaves. Physical environmental conditions can exert an effect on the interrelationships between the two species, but this experiment did not show the reversion of competition, and showed that E.crus-gilli was competitively dominant under any environmental conditions given in this study.

• 동력기계공학회지
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• 제4권1호
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• pp.81-87
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• 2000

In this study, CT specimens were prepared from ASTM SA516 Gr. 70 which was used for pressure vessel plates for room and low temperature service. And we got the following characteristics from fatigue crack growth test carried out in the environment of room and low temperature at $25^{\circ}C,\;-60^{\circ}C,\;-80^{\circ}C\;and\;-100^{\circ}C$ and in the range of stress ratio of 0.05 by means of opening mode displacement. At the constant stress ratio, the threshold stress intensity factor range ${\Delta}K_{th}$ in the early stage of fatigue crack growth (Region I) and stress intensity factor range ${\Delta}K$ in the stable of fatigue crack growth (Region II) was increased in proportion to descend temperature. It assumed that the fatigue resistance characteristics and fracture strength at low temperature is considerable higher than that of room temperature in the early stage and stable of fatigue crack growth region. The straight line slope relation of logarithm $d{\alpha}/dN\;-{\Delta}K$ in Region II, that is, the fatigue crack growth exponent m increased with descending temperature at the constant stress ratio. It assumed that the fatigue crack growth rate $d{\alpha}/dN$ is rapid in proportion to descend temperature in Region II and the cryogenic-brittleness greatly affect a material with decreasing temperature.

• 한국작물학회지
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• 제35권3호
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• pp.282-286
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• 1990

최근 미곡의 수확과 건조작업서 기계화와 동력화가 빠른 속도로 진행되고 있다. 벼 품종 추청과 밀양 2003를 재래식 낫과 콤바인으로 수확하고 천일건조, 개량곳간식, 인공화력식으로 건조하고 농기계 사용에 따른 곡물의 수확손실, 작업속도, 미립의 품질에 미치는 영향을 평가하였다. 1. 수확과정에서 낙립에 의한 포장손실은 콤바인을 사용하더라도 인력수확이나 차이 없었고 탈곡손실만은 콤바인 수확이 1.2% 가량 증가하였다. 소요작업시간은 콤바인 탈곡까지 완료하고도 3.5배 빨랐다. 품종간에 수확손실은 차이가 심하였는데 통일계인 밀양 2003가 일반계인 추정보다 약 2배의 손실량이 발생하였다. 2. 미곡의 건조방법별 건조속도는 수분함량 14%로 감소시키는데 인력수확후 천일건조는 10일이 소요되었으나 콤바인 수확후 천일건조는 5-9일이 걸렸고 개량곳간식은 2-3일, 화력건조는 15시간이 소요되었을 뿐이었고 계속 둘 경우 과건될 위험이 컸다. 3. 수확과 건조방법이 미립질에 미치는 영향은 완전미비율에서 화력건조가 가장 낮아 천일건조 보다 약 4% 저하하였으며 품종간에는 밀양 2003가 추청보다 낮은 경향이었다. 이것은 화력건조에서 동할미와 쇄미의 비율이 증가하였기 때문이었고 수확방법에 따른 미질의 영향은 콤바인 수확이 밀양 2003의 불완전미비율을 증가시켰으나 단립형인 추청은 영향을 받지 않았다.

• 한국초전도ㆍ저온공학회논문지
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• 제9권1호
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• pp.5-8
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• 2007

We have investigated the superconducting properties and surface morphology of $Sm_xBa_yCu_3O_{6+z}$ thin films deposited on LMO/IBAD-MgO/Hastelloy which prepared with different composition ratio by co-evaporation method(EDDC, Evaporation using Drum in Dual Chambers). We observed the composition ratio of SmBCO thin films by EDS analysis. We fabricated SmBCO thin film with critical current density of $1.5{\times}10^6A/cm^2$ at composition ratio of SM:Ba:Cu=1.10:2.01:3(at 77 K self-field). And, we confirmed that substitution of Sm-Ba did not occur at Cu rich phase by EDS analysis.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
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• pp.241-244
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• 2003

The world largest 21.3" LTPS LCD has been successfully developed using SLS crystallization technology. Successful integration of gate circuit, transmission gate and level shifter was performed in a large area uniformly. Uniformity and high performance from high quality grains of SLS technology make it possible to come true a uniform large size LTPS TFT-LCD with half number of data driver IC's used in typical a-Si LCD. High aperture ratio of 65% was obtained using an organic inter insulating method, which lead a high brightness of 500cd/cm2.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2006년도 추계 학술대회논문집
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• pp.181-184
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• 2006

High-speed flight vehicle have various cavities. The supersonic cavity flow is complicated due to vortices, flow separation and reattachment, shock and expansion waves. The general cavity flow phenomena include the formation and dissipation of vortices, which induce oscillation and noise. The oscillation and noise greatly affect flow control, chemical reaction, and heat transfer processes. The supersonic cavity' flow with high Reynolds number is characterized by the pressure oscillation due to turbulent shear layer, cavity geometry, and resonance phenomenon based on external flow conditions, The resonance phenomena can damage the structures around the cavity and negatively affect aerodynamic performance and stability. In the present study, we performed numerical analysis of cavities by applying the unsteady, compressible three dimensional Reynolds-Averaged Navier-Stokes(RANS) equations with the ${\kappa}-{\omega}$ turbulence model. The cavity model used for numerical calculation had a depth(D) of 15mm cavity aspect ratio(L/D) of 3, width to spanwise ratio(W/D) of 1.0 to 5.0. Based on the PSD(Power Spectral Density) and CSD(Cross Spectral Density) analysis of the pressure variation, the dominant frequency was analyized and compared with the results of Rossiter's Eq.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 추계학술대회 논문집
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• pp.349-354
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• 2011

Tuned mass damper is widely used in many applications of industry. The main advantage of tuned mass damper is that it can increase the damping ratio of system and reduce the vibration amplitude. Meanwhile, the natural frequency of system will be divided by two peaks, and the peak speeds are closely related to the mass and the stiffness of auxiliary mass system added. In addition, the damping ratio will also affect the peak frequency of the dynamic response. In the present research, the nonlinear mechanical characteristics of rubber is investigated and put into use, since it is usually manufactured as the spring element of tuned mass damper. By the sense of the nonlinear stiffness as well as the damping ratio which can be changed by preload applied on, the shape memory alloy is proposed to control the auxiliary mass system by self-optimizing. Supported by the experiment data of rubber, the 1 DOF theoretical model and finite element model based on computer simulation are implemented to perform the feasibility of the proposed semi-active tuned mass damper working on the drive shaft.