Numerical experiments were carried out to investigate the effect of data assimilation of observational data on weather and PM (particulate matter) prediction. Observational data applied to numerical experiment are aircraft observation, satellite observation, upper level observation, and AWS (automatic weather system) data. In the case of grid nudging, the prediction performance of the meteorological field is largely improved compared with the case without data assimilations because the overall pressure distribution can be changed. So grid nudging effect can be significant when synoptic weather pattern strongly affects Korean Peninsula. Predictability of meteorological factors can be expected to improve through a number of observational data assimilation, but data assimilation by single data often occurred to be less predictive than without data assimilation. Variation of air pressure due to observation nudging with high prediction efficiency can improve prediction accuracy of whole model domain. However, in areas with complex terrain such as the eastern part of the Korean peninsula, the improvement due to grid nudging were only limited. In such cases, it would be more effective to aggregate assimilated data.

교량 내하력 추정을 위해 제안된 모델에서는 응답계수를 충격계수 응답스펙트럼을 활용하여 산정하고 있다. 이때 충격계수 응답스펙트럼은 오일러-베르누이 보 모델을 바탕으로 차량이동하중이 교량의 폭 방향으로 중앙부에 재하 된 조건으로 생성된 결과이다. 따라서 중앙부 차량재하가 아닌 편측 이동하중재하 시 충격계수와 응답계수의 변화를 분석해 볼 필요가 있다. 이를 위해 본 연구에서는 폭이 10m인 2차선 단순교를 대상으로 이동하중해석을 실시하여 최대 충격계수와 응답계수 변화를 분석하였다. 수치해석 결과, 중앙부 재하조건 대비 편측 재하 조건 적용 시 최대 정적 및 동적 변위 모두 증가하지만 동적변위 보다 정적변위의 증가량이 더 크기 때문에 충격계수는 오히려 감소하게 된다. 하지만 이러한 차이는 0.5%p 미만으로서 그 영향이 크지 않다. 그리고 응답계수의 경우, 편측 재하조건으로 인해 정적응답계수보다 동적응답계수에서 차이가 더 크게 나타나지만 편측 재하에 따른 오차율의 차이는 0.18%p 정도로 매우 작았다. 즉, 편측 이동하중재하가 응답계수에 미치는 영향은 거의 없으며, 응답계수 산정에 있어서 중앙부 이동하중재하 조건으로 생성된 충격계수 응답스펙트럼을 활용하여도 충분한 예측이 가능하다고 판단된다.

The aim of this study was to determine the appropriate stockpiling methods for revegetation by comparing the germination status of seed banks before and after preservation for 2 years. Soil temperature in stockpiled topsoil was higher in open treatment and at 1.5 m, whereas soil water content was maintained at lower levels (14.06-19.08%), than those in the control group. The seed banks in stockpiled topsoil had 48 species and 1,559 individuals, among which perennials showed the highest number in terms of life forms, whereas Compositae and Gramineae were dominant in terms of families. Based on seed bank type, persistent seed banks had the highest number of species, while transient seed banks had the highest number of individuals. By stockpiling period, the number of species in the seed bank started to increase after 24 months, while the number of individuals began increasing after 12 months and exceeded that of the control group after 24 months. Regarding the treatment of stockpiling methods, the number of species and individuals in open treatment were closer to those of the control group. When analyzed by height, the number of species and individuals were higher at 0 m, but still lower than those of the control group. A multivariate analysis of variance (MANOVA ) showed that the optimal combination was obtained in open treatment and the number of individuals increased with the lengthening of the stockpiling period.

In this study, the behavior of composite concrete under low velocity impact with various temperature condition was assessed. The displacement-time curve from the experimental device impactor was utilized. The results showed that there is a significant change in the ductility when composite material is used at different temperature condition.

In this study, it evaluate the impact resistance of UHPC by repeated impact. smooth steel fiber and polyvinyl alcohol fiber were reinforced in UHPC respectively. Overall, the impact resistance of the specimens reinforced with 0.4vol.% PVA fiber was high, and the crater diameter was small in specimens using 13mm fiber.

The second impact from the edge of cargo was found to be an crucial event causing large volume loss of concrete median barrier. Therefore, in order to improve local impact resistance of concrete median barrier during second impact, local model was developed and evaluations were conducted. Developed concrete median barrier showed the 125 kJ impact level based on conducted analysis.

In this study, we proposed a modified design equation for SC walls subjected to local impact load based on a series of experimental studies on the impact resistance of SC walls. Then, the results of the modified design equation was evaluated and verified based on the extensive experimental test data as well as numerical parametric analysis data. Finally we confirmed that the modified design equation provided reasonable results.

The impact factor response spectrum of bridges are generated based on the number of vehicle axles (one and three axles) and their boundary conditions (simply supported and both ends-fixed). In order to investigate the impact factor variation, a RC slab bridge aged over 40 years is considered. The natural frequencies for the current and undamaged initial state are evaluated from field test and FE model, respectively. Considering the natural frequencies and the generated response spectrum, the impact factors for each state are determined. From the result, the impact factor ratio defined the current to initial impact factor are almost same except the one axle and both ends-fixed case.

The Korean environmental impact assessment(EIA) system, and explored ways to improve it as a more efficient and viable institution relevant to the demand of our time and conditions in study. The first problem this study identified is found in the fact that the party to write up the assessment report is itself the business operator or the one who is planning to work out the business plan. This structure translates into placing an order with an agent for EIA report. The reporting job may br subcontracted to the agent at a cost far below the rate specified in the ‘Standard for Estimate of Agency Fee for Environmental Impact Assessment.’ This practice also causes the vicious circle of producing a report that is written to justify the project or business in question or it leads to rough-and ready and poor documentation to minimize the time required. Second, in order to achieve the goal of the plan or business, which is the target of EIA, the local residents tend to ve regarded as an obstacle. This means elimination of the local people from participating in the EIA or their opinion being frequently ignored. This is the seed of distrust and hostility that sometimes provoke disagreements or fierce conflicts. The first proposal to improve these problem is to improve the factors that cause poor documentation of the assessment report as well as improve the understanding of the EIA system. This study proposes the following measures for improvement. The agency cost for EIA should be paid by the business operator or a third party that can ensure faithful implementation of the payment. A system should be established to verify transparent estimation of the agency cost. In order to enhance the professional quality of EIA agents, there should be implementation of qualification test for industrial engineer of related engineers in addition to the current EIA Qualification Test. The second proposal for improvement is to improve the citizen participation process by instituting a legal framework to make clear the purpose of the briefing session for local residents, which is held as a procedure of EIA, and to ensure more positive publicity during the stage of listening to the opinion of the local community. For a smooth and rational communication process, a moderator and a communicator of opinion, as is the case in a public hearing, could be instituted to clearly get the purpose of the briefing session across to the residents and to help to carry out the explanation and Q & A sessions according to the categories of the opinion of the residents. At present, the notification of the public inspection of the draft of the assessment report and briefing session for the residents is made on the newspaper and internet network. But some people have difficulty with access to this method of announcement. A higher participation rate could be secured if a legal provision is added to specify putting up placards in specific places such as the entrance to the place for the briefing session for residents or the building of administrative agencies of the area concerned.

Background : Polygonatum is a perennial herbaceous crop that is further classified into P. falcatum A. Gray (wild vegetation of Jeju, Japan), P. sibiricum F. Delaroche (wild vegetation of Korea north, China, Russia, and Mongol), and P. stenophyllum MAx (wild vegetation of South of Danyang), with the herbal name of Rhizoma polygonati. Polygonatum is harvested after 5 - 6 years since planting, and the quality of the radicle is a major factor determining the quantity of harvest. This study presents the morphological characteristics to predict the later quantity of radicles when planting polygonatum, and develops the methods for the prediction. Methods and Results : This study investigated the ground-level growth and the quantity of radicles in underground in 5-years-old, 4-leaf, 5-leaf, and 6- or more leaved polygonatum planted in the Chungbuk Agricultural Research and Extension Services. According to the investigation on the ground-level growth by the number of leaves, the 5-leaved plant showed the best plant length and nodal leaf number; 171 ㎝ and 24/stock, respectively. On the other hand, the leaf number and leaf weight were as heavy as 85 leaves and 58.3 g/stock, respectively, in 6-leaved plants or plants with more leaves. The leaf area was as wide as 15.6 ㎠ with 5-leaved plant, and the chlorophyll was also high. The investigation on the underground growth showed the best results in 6-leaved plants or plants with more leaves: the root length was 23.8 ㎝, number of radicle node was 5.7, and root weight was 291 g. The quantity was highest at 2,148 ㎏/10 a with 6-leaved plants or plants with more leaves, and at the lowest at 907 ㎏/10 a in 4-leaved plants. The profit analysis showed a profit of 3,859,000 won/5 years in 6-leaved plants or plants with more leaves, which 86% higher than the 4-leaved plants. Conclusion : If plants with6-leaf or more leaves at the ground level are selected and used as radicles for new polygonatum packaging, the quantity of radicles has increased by 59% and the profit increased by 86%, compared to 4-leaved plants.

The purpose of this study is to estimate the thickness of concrete slabs using the impact echo method based on the stress waves, which is one of the nondestructive test method, to evaluate the safety and construction conditions of concrete slabs. If the correlation and reliability of the impact echo method and the slab thickness are secured, it can be considered that the quality control of the concrete slab is possible in existing structures and structures under construction.

One of the indicators evaluate the bridge load bearing capacity is the peak impact factor. The peak impact factor is related to vehicle types and speeds and frequency of the bridges. Among the parameters, the vehicle types such as DB-24 and standard vehicle load presented in the current specification have different load distribution and different load axles space. Considering these features, in the present study, the variation of the peak impact factor according to each vehicle type is investigated and compared.

In this study, we performed a series of experimental studies on the effect of tie-bars and steel-plate strength on the impact resistance of SC walls. A total of 8 impact tests were planned to investigate the impact resistance performance of SC walls at the extreme performance testing center of Seoul National University in Korea. The specimens were designed with the main test parameters of yield strength of steel plate and tie-bars. The results from this study will be used to improve and optimize the AISC N690 design equation for SC walls.

This paper has developed a Derailment Containment Provision(DCP) between rails to prevent derailed accident of the train. And developed DCP under impact loading was analytically evaluated using LS-Dyna. This paper was simulated using Mat_72R3 and Mat_CSCM for concrete material. To modify the developed DCP, this paper was suggested suitable and reasonable analytical concrete material model.

A detailed guideline was prepared to explain the contents of underground safety management guideline and to prevent confusion in the initial implementation of the law to underground safety impact assessment and underground safety inspection subjects. "Special Law on Underground Safety Management", which was created to prevent the safety of the people from frequent occurrences due to frequent occurrence of subsidence, has been systematically settled in the course of design, construction and maintenance of underground facilities. When it works smoothly, it can be said that national security is guaranteed.

Climate change has caused localized torrential rainfalls and typhoons to occur more frequently, increasing damages to both life and property. In particular, debris flows have brought damages not only in mountainous areas but also in urban centers. Many studies have been carried out with the rising concern on debris flows. These studies applied different debris flow models and conduct analyses on behaviors of debris flow and on forecasting. Given this, however, the subject of the impact force of debris flows should also be taken into consideration. Thus, this study applied RAMMS and FLO-2D, two models for the numerical analysis of debris flows used to analyze impact force. Here, the selected study areas are Umyeonsan Mountain in Seoul and Majeoksan Mountain in Chuncheon, where damages on debris flows were caused by the localized heavy rains in 2011. To identify a debris flow–triggering rainfall, we used and applied rainfalls calculated at different frequencies (30-year, 50-year, 100-year, 200-year). This study calculated and compared impact forces produced by the two models at any point in the study areas. Identifying impact forces based on the comparison of the two models will be useful in selecting materials and equipment appropriate when installing facilities in mountainous regions.

In this study, we investigated the impact of different initial data on atmospheric modeling results using the Weather Research and Forecast (WRF) model. Four WRF simulations were conducted with different initialization in March 2015, which showed the highest monthly mean PM10 concentration in the recent ten years (2006-2015). The results of WRF simulations using NCEP-FNL and ERA-Interim were compared with observed surface temperature and wind speed data, and the difference of grid nudging effect on WRF simulation between the two data were also analyzed. The FNL simulation showed better accuracy in the simulated temperature and wind speed than the Interim simulation, and the difference was clear in the coastal area. The grid nudging effect on the Interim simulation was larger than that of the FNL simulation. Despite of the higher spatial resolution of ERA-Interim data compared to NCEP-FNL data, the Interim simulation showed slightly worse accuracy than those of the FNL simulation. It was due to uncertainties associated with the Sea Surface Temperature (SST) field in the ERA-Interim data. The results from the Interim simulation with different SST data showed significantly improved accuracy than the standard Interim simulation. It means that the SST field in the ERA-Interim data need to be optimized for the better WRF simulation. In conclusion, although the WRF simulation with ERA-Interim data does not show reasonable accuracy compared to those with NCEP-FNL data, it would be able to be Improved by optimizing the SST variable.

콘크리트 구조물이 화재 손상을 입을 경우 노출온도 및 지속시간에 따라 구조물의 심각한 성능 저하를 야기하며, 콘크리트의 재료 물성 저하를 수반한다. 화재 손상을 입은 콘크리트 구조물의 재사용여부 및 보수보강 판단을 위해서는 손상 직후 및 재양생 조건에 따른 주요 손상 부위의 면밀한 손상 평가가 필요하다. 본 연구에서는 재양생 조건에 따른 화재 손상을 입은 콘크리트의 재료물성 회복에 관한 실험적 연구 를 수행하였다. 화재 손상을 입은 콘크리트 시편을 상대습도 및 재양생 기간을 달리한 재양생 조건을 적용하였으며, 충격공진기법을 도입하여 콘크리트 시편의 화재 손상 전후 및 재양생 이후의 동탄성계수를 측정하여 손상 정도를 평가하였다. 측정된 결과로부터 재양생 조건 중 높은 상 대습도 조건에서 지배적으로 재료물성의 회복이 발생하였다. 추가적으로 콘크리트 시편의 동탄성계수 및 인장강도의 직접적인 비교 및 선형 회귀분석을 수행하여 재양생 조건에 따른 영향을 분석하였으며, 이를 토대로 높은 습도 조건에서 동탄성계수의 회복이 인장강도에 비해 두드 러지게 나타남을 확인하였다.

This study was evaluated dynamic impact tensile properties of 80 MPa sprayed HPFRCC by I-SEFIM test as a part of the research for development of sprayed HPFRCC for protection and blast resistant of existing structures.

In this study, collision analysis of overlay concrete median barrier under truck load was conducted depending on location of rebar and shear key. Obtained results indicates that the impact resistances of overlay concrete median barrier was improved as the rebar and shear keys are more closed to the top surface of the CMB.