Earticle

본 연구에서는 하천실험센터에서 부유 물질 실험을 수행하여 부유 물질의 거동 및 확산을 관찰하고 이를 입자분산모형을 통하여 그 이동을 구현하고자 하였다. 규사를 물과 믹서기를 이용하여 혼합한 후 실규모 크기의 실험수로에 인위적으로 투입하고 레이저부유사측정기(LISST)를 이용하여 부유 물질의 농도를 측정하였다. 실험에 서 드론 이미지 및 부유사 측정기 관측 데이터와 입자 분산 모형을 통해 부유 물질의 거동을 모의하여 비교한 결과, 비교적 실험 결과가 구현이 잘 된 것을 확인할 수 있었다. 이를 통하여 입자 분산 모형의 적용성은 물론, 높은 강우 량으로 인한 유량 발생 시 부유 물질 예측 활용성을 기대할 수 있게 되었다.

In this research a suspended solid transport experiment was conducted in the river experiment center to find the characteristics and dispersion of the material. Modeling by the particle dispersion model was also executed to reproduce the suspended solid transport. The suspended solid was consisted of a mixture of silica and water using a mixing equipment, which was then introduced into a real-scale flume and measured with the laser-diffraction based particle size analyzer(LISST) to find the concentration of the material. The comparison between the measured suspended solid concentration using drone images and particle size analyzers, with the model showed a good match overall, which proved the applicability of the model. Along with finding the model applicability, the research showed the potential for suspended solid estimation in high flow situations with high rainfall.

In this study, an investigation was conducted to assess the washout mechanism of Asian dust particles through both laboratory-scale experiment and model calculation. To artificially simulate Asian dust particle, $CaCO_3$ particles were generated inside an experimental chamber. They were then scavenged by the artificial rain drops. The abundant $CaCO_3$ particles scavenged on a rain drop were successively identified by SEM observation. The concentrations of Ca in residual $CaCO_3$ particles on individual droplet were quantified by PIXE analysis. There was a tendency toward a high accumulation of Ca on a relatively small drop (e.g., <1.0 mm diameter). It is thus suggested that smaller rain drops can effectively scavenge a significant amount of Asian dust particles in ambient atmosphere. The numerical estimation can account for 92.1% and 83.2% of Ca that were measured in small (<1.0 mm diameter) and large (>2.0 mm diameter) size drops, respectively.

Fire characteristics of a typical apartment building in Korea was studied through full scale experiment and zone model simulation. The fire was ignited at the living room and allowed to spread to other parts of a single unit in a five storied apartment building. Various data including temperatures, species concentrations, and images were collected in the experiment. A zone model(CFAST) was used to analyze the same apartment building that represents the average households in Korea. The results were compared with a full scale experiments. While CFAST allows one compartment involved with fire, the experiment allowed the fire to spread to other compartments. Therefore, the comparison between experimental data and Zone-Model data is valid until the living-room fire spread to other parts of the apartment. Flashover occurred at approximately 380 seconds in a fire experiment, and at approximately 420 seconds in Zone-Model. Based on all of data between experimental data and Zone-Model data, it is concluded that the safe escape time is about 250 seconds.

The OGS model is configured and used for simulation of the LASGIT project. The modeling conditions and the simulation results from the previous work by Walsh and Calder (2009) are analyzed to see if the simulation configuration is done correctly and to apply for the LASGIT project. Except for the unrealistic modeling conditions used previously, the simulation results successfully demonstrated helium propagation that is typical for the two-phase flow. The results indicated that the relations of capillary pressure and the relative permeability against water saturation used previously should be updated. An elaborated simulation with more realistic parameters should be used to improve the weak points of preliminary work.

현재 국내의 침윤소화약제 기술기준은 표면장력에 대한 기준만 존재하여 이를 통한 약제의 성능평가는 어려운 실정이다. 따라서 침윤소화약제의 성능평가 기법을 제시하기 위해 축소모형 실험 장치를 통한 최적화된 성능평가 방법을 제시하고자 한다. 본 연구는 해외 기준인 NFPA 18의 실험과 자체 제작된 축소모형 실험 장치를 이용한 실험의 결과 비교분석을 통해 자체 제작 축소모형 실험 장치실험 결과의 타당성을 규명하고자 한다. 목화솜을 대상으로 침투성능만을 평가하는 NFPA 18 실험과 목분을 대상으로 침투성능과 소화성능을 모두 평가하는 축소모형 실험을 비교분석한 결과 NFPA 18의 실험과 자체 제작 축소모형 실험에서 모두 소화용수의 침투성에 관한 변별력을 확인할 수 있었다. 또한 자체 제작 축소모형 실험에서는 T/C를 통한 내부온도 측정을 통해 보다 명확한 변별력을 나타냄을 확인하였다.

A current standard exist only on the surface tension in the current domestic wetting agent technology standards, so it is difficult to the performance evaluation of the wetting agent through the standard. So this study presents the optimized performance evaluation methods by scale model experimental equipment in order to present techniques for performance evaluation of wetting agents. The purpose of this study is to investigate validity of experimental results of the self-designed scale model experiment equipment by a comparative analysis of experimental results of the NFPA 18 experiment and the experiment using the self-designed scale model experiment equipment. As a result of a comparative analysis of experimental results of the NFPA 18 experiment that evaluate only the permeation performance on the contton and the experiment using the self-designed scale model experiment equipment that evaluate the permeation performance and fire extinguishing performance on wood flour, the discrimination of the permeation performance was confirmed in both the NFPA 18 experiment and the self-designed scale model experiment equipment. And a result of self-designed experiment equipment have clear discriminatory more than NFPA 18 by internal temperature measurement using the thermocouples.

Noise radiated from pile driving operation is one of major sources of community noise pollution and thus its operation method is strictly restricted by regulations. Although the drilling method is now used been commonly used in urban areas because of its activity, the benefit of low noise decreases due to high working cost. In the present work, noise characteristics of pile driving operation are carried out. Based on the study result, a low-noise pile cap for driven piles is developed in order to satisfy both the noise level restriction and the economical efficiency. Effects of pile cap are investigated by a scale model experiment, which is focused on the variation of impact force and sound pressure level. The results show a good possibility of noise reduction by an appropriately designed pile cap.

전차선로와 팬터그래프로 이루어진 집전계에서 두 계 사이의 기계적 상호 작용이나 이선과 같은 집전 특성은 직접 현장 시험을 통하여 확인하는 것이 가장 정확하고 확실한 방법이며, 꼭 필요한 것으로 여겨지고 있다. 그러나 고속이 될수록 집전 성능을 직접 현장에서 시험을 통하여 실시하는 것은 경제적으로나 현실적으로 불가능한 경우가 대부분이다. 그래서 대안으로 시뮬레이션 방법이 이용되기는 하나 이것은 현장 시험을 대체하는 방법이 아닌 하나의 보조적인 방법에 불과하다. 그래서 대안으로 컴퓨터를 이용한 시뮬레이션 방법이 이용되고 있다. 그러나 이것은 유용한 방법이긴 하나 현장 시험을 대체하는 방법이 아닌 하나의 보조적인 방법으로 간주되고 있는 것이 일반적인 관점이다. 그래서 실제 속도의 현장 시험에 대한 하나의 대안으로 속도 축척 모형의 집전계 주행시험기를 이용하는 방법이 있다. 이것은 실제 속도의 1/2이나 1/4 정도의 속도에서 시험을 하면서 실제 속도에서의 특성을 확인하는 시험 방법이다. 본 논문에서는 이 속도 축척 모형 시험의 세부적인 시험 방법과 시험 설비에 대하여 알아본다. 그리고 이 방법으로 시험하였을 때 나타나는 성능이 실제 속도에서의 성능을 어느 정도 가깝게 나타내는지를 파악해 보고자 특정 속도와 조건을 선정하여 전차선로-집전계 사이의 동역학 시뮬레이션을 실시하여 보았다. 시뮬레이션 결과 특정 조건이 갖추어진다면 이 속도 축척 모형 시험 방법이 효용성이 있음을 확인할 수 있었다.

To test the current collection characteristics between overhead contact lines and pantograph in a real speed scale costs too much, therefore, it is very difficult to be realized especially in a high speed region. As a alternative, the speed scale-downed tests is proposed. In this paper, the experimental methodology and effectiveness of the speed scale-downed tests are discussed through the dynamic simulation evaluations. To get a more precise test results to the real speed scale test in the 1/2 and 1/4 speed scale-downed tests, various experimental conditions are discussed. Throughout the simulation in a various conditions the effectiveness are evaluated.