• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1998년도 지반조사위원회 여름 학술세미나
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• pp.51-80
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• 1998

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1996년도 봄 학술발표회 논문집
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• pp.251-258
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• 1996

• 한국자동차공학회논문집
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• 제17권2호
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• pp.82-89
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• 2009

In order to investigate the spray characteristics according to diesel and bioethanol blending with biodiesel fuel, macroscopic spray characteristics were analyzed from the comparison of the effect of the injection pressure, ambient pressure and density on the spray tip penetration and spray cone angle. In addition, spray atomization characteristics were studied with local and overall Sauter mean diameter (SMD) and the contour map of SMD distribution at various injection conditions. It was revealed that the spray tip penetration of biodiesel fuels blended with diesel and ethanol was shorter than that of an undiluted biodiesel fuel at low injection pressure. However, the difference of spray tip penetration among three test fuels reduces at a high injection pressure. Increase of the ambient gas density leads to the decrease of the spray tip penetration of three test fuels. When diesel and ethanol fuels add to an undiluted biodiesel fuel, spray cone angle increases due to the decrease of the fuel density at the same ambient pressure condition. On the other hand, the droplet mean diameter decreases due to the reduction of the kinematic viscosity and surface tension.

• 한국화재소방학회논문지
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• 제26권1호
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• pp.89-95
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• 2012

본 연구에서는 목분-HDPE 복합체를 모듈라 회전 이축압출기를 이용하여 제조하여 연소성 및 열적특성을 평가하기 위하여 콘칼로리미터 실험및 열중량 분석실험을 실시하였다. 그리고 복합체의 난연성능 향상을 위하여 난연제(3종)를 첨가한 복합체의 화재성능을 평가하였다. 콘칼로리미터 실험 결과 난연제를 첨가하지 않은 복합체의 열방출률이 가장 높았으며 최대 열방출률 값은 $446.6kW/m^2$, 평균 열방출률 값은 $185.5kW/m^2$으로 가장 높게 나타났다. 열중량 분석 결과 난연제 첨가한 복합체들의 열분해가 먼저 시작되고 열 안정성을 향상시켰다.

• Journal of Astronomy and Space Sciences
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• 제32권4호
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• pp.317-325
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• 2015

Energy spectra of electron microbursts from 170 keV to 340 keV have been measured by the solid-state detectors aboard the low-altitude (680 km) polar-orbiting Korean STSAT-1 (Science and Technology SATellite). These measurements have revealed two important characteristics unique to the microbursts: (1) They are produced by a fast-loss cone-filling process in which the interaction time for pitch-angle scattering is less than 50 ms and (2) The e-folding energy of the perpendicular component is larger than that of the parallel component, and the loss cone is not completely filled by electrons. To understand how wave-particle interactions could generate microbursts, we performed a test particle simulation and investigated how the waves scattered electron pitch angles within the timescale required for microburst precipitation. The application of rising-frequency whistler-mode waves to electrons of different energies moving in a dipole magnetic field showed that chorus magnetic wave fields, rather than electric fields, were the main cause of microburst events, which implied that microbursts could be produced by a quasi-adiabatic process. In addition, the simulation results showed that high-energy electrons could resonate with chorus waves at high magnetic latitudes where the loss cone was larger, which might explain the decreased e-folding energy of precipitated microbursts compared to that of trapped electrons.

• 지구물리
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• 제7권1호
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• pp.23-30
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• 2004

국내 건설현장에서는 성토다짐의 다짐도 확인을 위해 주로 평판재하시험(PBT)을 사용한다 평판재하시험은 재하시험시 표층의 매우 잘 다져진 곳에 대한 지지력 계수를 획득하여 실다짐도를 과대 평가하는 결과를 초래할 수 있다. 이에 착안하여 응력도달 범위가 작은 평판재하시험을 지양하고 콘관입시험으로부터 획득되는 노상의 관입지수로부터 지반의 다짐도를 추정할 수 있는 콘관입시험기와 구동시스템 및 해석 프로그램을 개발하였다. 개발된 시스템은 다짐차량에 간편하게 부착하여 현장에서 직접 다짐도를 획득할 수 있으며 다짐도와 더불어 다져진 지반의 전단강도정수를 동시에 측정할 수 있다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 추계 학술발표회 3차
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• pp.18-23
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• 2010

The estimation of the undrained shear strength $s_u$ for clays using CPT results has been mainly based on the cone factor $N_k$. In this study, a new CPT-based method for the estimation of the undrained shear strength $s_u$ is presented. This aims at reducing uncertainties for the estimation of $s_u$ and enhancing the application of CPT results in more effective manner. For this purpose, a site located at a marine clay deposit is selected and test results from extensive experimental testing program are adopted. The new method defines a direct correlation between the undrained shear strength $s_u$ and the cone resistance $q_t$, excluding the procedure of the overburden pressure correction and therefore undisturbed soil sampling process. In order to verify the new CPT-based method, additional test sites and example sites from literature, which consist of a variety of soil conditions, are selected and examined. It is observed that values of su obtained from the proposed method are in good agreements with measured values of $s_u$ for all the selected verification cases.

• 한국화재소방학회:학술대회논문집
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• 한국화재소방학회 1997년도 International Symposium on Fire Science and Technology
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• pp.85-92
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• 1997

Flammability of non-flame-retardant and flame-retardant materials was studied by using cone calorimeter Also, relations between the results obtained by using cone calorimeter and those obtained by the flammability test of japanese fire Service Law were examined. The results are as follows: 1) The ignition time of the molten specimens is relatively long, whereas the ignition time of the non-molten specimens is short. None of remarkable difference of the ignition time has been found between non-flame-retardant and flame-retardant materials specimens. 2) The peak heat release rates of flame-retardant materials are smaller than those of non-flame- retardant materials. 3) The carbon monoxide and smoke evolved from flame-retardant materials generate much more than those evolved from non-flame-retardant materials. 4) Even if flame-retardant materials are passed by the flammability test of Japanese Fire Service Law, they burn easily under external radiative heating condition.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2012년도 제38회 춘계학술대회논문집
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• pp.230-237
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• 2012

확대부 내열재의 스틸과 FRP 사이에 존재하는 미접착 결함과 미충전 결함을 검출하기 위해 초음파 공진법을 적용하였다. 초음파 공진법은 초음파 신호가 증폭되기 때문에 펄스에코법으로 검출하기 어려운 미접착 결함 및 에폭시 미충전 결함을 쉽게 검출할 수 있다. 공진 주파수는 삼중 매질의 음압 반사계수를 이용하여 예측하였고, 시험편의 초음파 신호에 대해 고속푸리에변환을 실시하여 측정하였다. 예측한 공진 주파수는 측정한 공진 주파수와 일치하므로 초음파 공진을 입증하였다.

• 한국지반공학회논문집
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• 제28권2호
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• pp.5-14
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• 2012

현장 다짐기에 가속도계를 이용한 연속다짐 평가장치를 부착하여 얻은 지반의 지지력 평가값 및 기존의 다짐도 평가장치의 결과 값들을 회귀분석하여 비교하였다. 회귀분석 평가 결과, 특정 성토재료에서 Geogauge와 동적콘관입시험은 기존 다짐도 평가(평판재하시험 및 다짐도시험) 결과와의 상관관계가 거의 없는 것으로 나타났다. 또한 CMV를 이용한 평가법이 기존 다짐도 평가를 대체할 수 있는지를 알아보기 위하여 여러 가지 다짐도 평가를 실시하였다. 그 결과 가속도계를 이용한 CMV는 다져진 지반의 강성 특성을 빠르고 편리하게 평가할 수 있을 것으로 판단된다.