• Journal of The Korean Society of Agricultural Engineers
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• v.55 no.6
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• pp.57-68
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• 2013

About 74 % of reservoirs in Korea are older than 40 years and their storage capacities have been decreased substantially. As part of reservoir reinforcement, the dam heightening project has been ongoing for about 110 reservoirs. The main purpose of the dam heightening project is to secure additional environmental water, while improving flood control capacity by gaining additional storage volume. The objective of this study was to evaluate reservoir flood control capacity changes of dam heightening reservoirs for effective management of additional storage volume. In this study, 13 reservoirs were selected for reservoir simulation of 200 year return period floods. Rainfall data of 1981-2100 were collected and divided into 4 periods (1981-2010; 1995s, 2011-2040; 2025s, 2041-2070; 2055s, 2071-2100; 2085s). Probability rainfalls and 200yr design floods of each period were calculated using FARD2006 and HEC-HMS. Design floods were used as inputs of each reservoir simulation using HEC-5. Overall, future probability rainfalls and design floods tend to increase above the past 1995s. Control ratios were calculated to evaluate flood control capacities of reservoirs. As a result, average flood control ratios were increased from 32.6 % to 44.2 % after dam heightening. Control ratios were increased by 12.7 % (1995s), 12.4 % (2025s), 10.3 % (2055s) and 10.9 % (2085s). The result of this study can be used as a basis for establishing the reservoir management structure in the future.

• International Journal of Control, Automation, and Systems
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• v.4 no.3
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• pp.325-332
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• 2006

The dynamic responses of human standing postural control were investigated when subjects were exposed to long-term horizontal vibration. It was hypothesized that the motion of standing posture complexity mainly occurs in the mid-sagittal plane. The motor-driven support platform was designed as a source of vibration. The AC Servo-controlled motors produced anterior/posterior (AP) motion. The platform acceleration and the trunk angular velocity were used as the input and the output of the system, respectively. A method was proposed to identify the complexity of the standing posture dynamics. That is, during AP platform motion, the subject's knee, hip and neck were tightly constrained by fixing assembly, so the lower extremity, trunk and head of the subject's body were individually immovable. Through this method, it was assumed that the ankle joint rotation mainly contributed to maintaining their body balance. Four subjects took part in this study. During the experiment, the random vibration was generated at a magnitude of $0.44m/s^2$, and the duration of each trial was 40 seconds. Measured data were estimated by the coherence function and the frequency response function for analyzing the dynamic behavior of standing control over a frequency range from 0.2 to 3 Hz. Significant coherence values were found above 0.5 Hz. The estimation of frequency response function revealed the dominant resonance frequencies between 0.60 Hz and 0.68 Hz. On the basis of our results illustrated here, the linear model of standing postural control was further concluded.

• Steel and Composite Structures
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• v.39 no.5
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• pp.615-630
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• 2021

The main purpose of the present work was to study the dynamic instability of a three-layered, thick composite sandwich beam with the functionally graded (FG) flexible core subjected to an axial compressive follower force. Flutter instability of a sandwich cantilever beam was analyzed using the high-order theory of sandwich beams, for the first time. The governing equations in general for sandwich beams with an FG core were extracted and could be used for all types of sandwich beams with any types of face sheets and cores. A polynomial function is considered for the vertical distribution of the displacement field in the core layer along the thickness, based on the results of the first Frosting's higher order model. The governing partial differential equations and the equations of boundary conditions of the dynamic system are derived using Hamilton's principle. By applying the boundary conditions and numerical solution methods of squares quadrature, the beam flutter phenomenon is studied. In addition, the effects of different geometrical and material parameters on the flutter threshold were investigated. The results showed that the responses of the dynamic instability of the system were influenced by the follower force, the coefficients of FGs and the geometrical parameters like the core thickness. Comparison of the present results with the published results in the literature for the special case confirmed the accuracy of the proposed theory. The results showed that the follower force of the flutter phenomenon threshold for long beams tends to the corresponding results in the Timoshenko beam.

• Clinical and Experimental Reproductive Medicine
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• v.49 no.3
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• pp.175-184
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• 2022

Objective: The aim of this study was to evaluate the impacts of platelet-rich plasma (PRP) and conditioned medium (CM) derived from endometrial stromal cells on mouse preantral follicle culture in a two-dimensional system to produce competent mature oocytes for fertilization. Methods: In total, 240 preantral follicles were isolated from female mouse ovarian tissue and divided into four groups. The preantral follicles were isolated three times for each group and then cultured, respectively, in the presence of alpha minimum essential medium (control), PRP, CM, and PRP+CM. The in vitro growth, in vitro maturation, and cleavage percentage of the preantral follicles were investigated. Immunocytochemistry (IHC) was also conducted to monitor the meiotic progression of the oocytes. Additionally, the mRNA expression levels of the two folliculogenesis-related genes (Gdf9 and Bmp15) and two apoptosis-related genes (Bcl2 and Bax) were investigated using real-time polymerase chain reaction. Results: In the PRP, CM, and PRP+CM groups, the preantral follicle maturation (evaluated by identifying polar bodies) were greater than the control group. The cleavage rate in the CM, and PRP+CM groups were also greater than the control group. IHC analysis demonstrated that in each treatment group, meiotic spindle was normal. In the PRP+CM group, the gene expression levels of Bmp15, Gdf9, and Bcl2 were greater than in the other groups. The Bax gene was more strongly expressed in the PRP and control groups than in the other groups. Conclusion: Overall, the present study suggests that the combination of CM and PRP can effectively increase the growth and cleavage rate of mouse preantral follicles in vitro.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.329-329
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• 2021

우리나라의 농촌유역은 일반적으로 상류의 농업용저수지와 하류의 배수장을 통해 홍수조절이 이루어지며, 각 농업수리구조물의 운영이 유역의 홍수 및 침수 발생에 큰 영향을 끼친다. 농촌유역의 홍수 대응 능력을 향상시키기 위해서는 농업수리구조물의 통합적 운영이 필요하나 현실에서 이를 시험 운영하기 위해서는 시간적·경제적으로 한계가 있다. 따라서 농촌유역 내 농업수리구조물을 연계한 통합 해석 시스템을 활용하여 다양한 구조물 운영 시나리오에 따른 홍수 위험을 예측하고 효율적인 대응 방안을 마련할 필요가 있다. 본 연구에서는 농업수리구조물을 연계한 홍수·침수 모의 시스템을 구축하기 위하여, 농촌유역에서 홍수·침수 모의를 위한 요소별 모듈을 구성하고, 각 모듈의 연계 기술을 개발하였다. 홍수·침수 해석 모듈은 농업용저수지 상류 유역에서부터 하류 하천 및 농경지까지 통합적으로 분석할 수 있도록 강우 분석 모듈, 강우-유출 모듈, 저수지 운영 모듈, 하천 수위 모듈, 농경지 배수 모듈의 5가지로 구성하였으며, 데이터베이스 모듈을 통해 기초자료를 저장하고 모듈 간의 입출력 과정을 처리하였다. 강우 분석, 강우-유출, 농경지 배수 모듈은 python 코드를 기반으로 자체적으로 구축하였으며, 기존의 모형 (FARD, HEC-HMS, GATE2018)들과 비교한 결과 거의 동일한 모의 결과를 나타냈다. 저수지 운영 모듈과 하천 수위 모듈은 각각 미 공병단의 HEC-5, HEC-RAS 모형을 CLI (Command Line Interface) 방식으로 외부 구동하도록 구성하였다. 전체 모듈 간의 연계에는 python 라이브러리인 Dask를 적용하여 대량의 데이터에 대한 병렬 처리 구조를 갖춤으로써 다양한 기상자료와 운영 시나리오에 따른 반복 작업을 효율적으로 수행하도록 구성하였다. 본 연구에서 개발한 홍수·침수 모의 요소별 모듈과 연계 기술을 기반으로, 농업수리구조물의 연계 운영을 통합적으로 모의함으로써 홍수 대비를 위한 효율적인 구조물 운영안을 도출할 수 있을 것으로 기대된다.

• International conference on construction engineering and project management
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• 2013.01a
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• pp.279-286
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• 2013

This paper introduces a new method for identification of building energy performance problems. The presented method is based on automated analysis and visualization of deviations between actual and expected energy performance of the building using EPAR (Energy Performance Augmented Reality) models. For generating EPAR models, during building inspections, energy auditors collect a large number of digital and thermal imagery using a consumer-level single thermal camera that has a built-in digital lens. Based on a pipeline of image-based 3D reconstruction algorithms built on GPU and multi-core CPU architecture, 3D geometrical and thermal point cloud models of the building under inspection are automatically generated and integrated. Then, the resulting actual 3D spatio-thermal model and the expected energy performance model simulated using computational fluid dynamics (CFD) analysis are superimposed within an augmented reality environment. Based on the resulting EPAR models which jointly visualize the actual and expected energy performance of the building under inspection, two new algorithms are introduced for quick and reliable identification of potential performance problems: 1) 3D thermal mesh modeling using k-d trees and nearest neighbor searching to automate calculation of temperature deviations; and 2) automated visualization of performance deviations using a metaphor based on traffic light colors. The proposed EPAR v2.0 modeling method is validated on several interior locations of a residential building and an instructional facility. Our empirical observations show that the automated energy performance analysis using EPAR models enables performance deviations to be rapidly and accurately identified. The visualization of performance deviations in 3D enables auditors to easily identify potential building performance problems. Rather than manually analyzing thermal imagery, auditors can focus on other important tasks such as evaluating possible remedial alternatives.

• Journal of Korea Water Resources Association
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• v.40 no.9
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• pp.697-707
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• 2007

In this study, we estimated the PMP(Probable Maximum Precipitation) and its transition in case of the typhoon Rusa which happened the biggest damage of all typhoons in the Korea. Specially, we analysed the moisture maximizing rate under the consideration of meteorological condition based on the orographic property when it hits in Gangneung region. The PMP is calculated by the rate of the maximum persisting 12 hours 1000 hPa dew points and representative persisting 12 hours 1000 hPa dew point. The former is influenced by the moisture inflow regions. These regions are determined by the surface wind direction, 850 hPa moisture flux and streamline, which are the critically different aspects compared to that of previous study. The latter is calculated using statistics program (FARD2002) provided by NIDP(National Institute for Disaster Prevention). In this program, the dew point is calculated by reappearance period 50-year frequency analysis from 5% of the level of significant when probability distribution type is applied extreme type I (Gumbel distribution) and parameter estimation method is used the Moment method. So this study indicated for small basin$(3.76km^2)$ the difference the PMP through new method and through existing result of established storm transposition and DAD(Depth-Area-Duration). Consequently, the moisture maximizing rate is calculated in the moisture inflow regions determined by meteorological fields is higher $0.20{\sim}0.40$ range than that of previous study. And the precipitation is increased $16{\sim}31%$ when this rate is applied for calculation.

• Journal of Wetlands Research
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• v.19 no.1
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• pp.30-36
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• 2017

SS(Suspended Solid) concentration by soil erosion into river at normal and flood season should be measured. However, to present the variation of SS due to various development project such as EIA(Environmental Impact Assessment), River Master Plan, and so on, it is necessary to estimate not measure SS, but there are not exist how to estimate SS. In the present study, therefore, we propose the hydrologic method of estimating SS concentration using the results of particular frequency flood discharge and sediment discharge by RUSLE method. SS consists of silty and clay soil and colloid particle etc. However, in the present study, silty and clay soils of sediment discharge except send set up SS standards. The flow discharge to estimate SS concentration are 1~2 years for normal season, 30~100 years for flood season. Meanwhile, analysis software for probable rainfall uses Fard2006, probable rainfalls under 2-year frequency are estimated using rainfall data and frequency factor of Gumbel distribution. The results of estimating SS concentration using runoff volume by sediment and flow discharges of silty and cray soils as above method show that reliable level of SS concentration is considered in predevelopment of natural condition and under development of barren condition. Especially, SS concentration takes notice that the value of sediment discharge makes a huge difference according to channel slope, it was confirmed that the value obtained by dividing the SS concentration by the channel slope is relatively constant even though the topographical factors are different. Therefore, if the present study will be proceeded for various watersheds, it will be developed as estimation method of SS concentration.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.764-769
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• 2006

본 연구에서는 최근에 빈번히 발생하는 단시간 집중호우양상의 변화와 자료기간의 누적에 따른 지속시간 및 재현기간별로 확률강우량의 변화양상을 분석하였다. 분석 대상 지점으로는 서울지점을 선정하였다. 강우자료는 기상청 산하의 강우관측소 자료를 이용하였으며 확률강우량 산정을 위한 강우지속시간은 10분, 20분, 30분, 40분, 50분 60분, 120분, 180분, 360분, 720분, 1440분을 지속시간으로 선정하였고 재현기간은 5년, 10년, 15년, 20년, 25년, 30년, 50년, 80년, 100년, 200년으로 수공구조물 설계시 많이 고려되어지는 재현기간을 선정하였다. 먼저 최근의 강우양상의 변화와 확률강우량의 경년변화 양상을 비교 분석하기 위하여 서울지점의 강우자료에 대한 장기 변동성을 분석하였고, 연강우량과 지속시간별 연 최대 강우량의 상관성을 분석하였다. 다음으로 통계적 분석을 통하여 확률강우량의 경년변화 양상을 지속시간 및 재현기간별로 분석하였다. 연강우량과 지속시간별 연최대강우량의 상관성 분석은 상호상관분석과 회귀분석을 실시하여 분석하였다. 확률강우량의 경년변화 분석 방법은 기본자료기간을 20년으로 산정하여 매해 강우자료를 추가하면서 확률강우량을 산정하여 경년변화를 살펴보았다. 확률강우량의 산정은 국립방재연구소와 연세대학교가 공동으로 제작한 FARD모형을 사용하였다. 분석결과 최근 강우량이 증가 추세에 있는 것을 확인 할 수 있었으며, 연강우량과 지속시간별 연 최대 강우량의 상관성은 없는 것으로 나타났다. 또한 확률강우량의 분석결과에서는 자료의 누적에 따른 확률강우량의 지속시간 및 재현기간에 따라 차이가 상이하며, 변동폭은 20% 내외로 나타났다. 토양수분 계산에도 영향을 준 것으로 보인다. 본 연구는 WEP 모형의 토양수분 해석능력에 대한 시험적용에 그 의의가 있으며, 향후 토양 및 지표하 매개변수 정보가 충분히 갖추어지고, 토양수분 관측결과 있는 대상유역에 대한 적용이 요구된다.-Moment 방법에 의해 추정된 매개변수를 사용한 Power 분포를 적용하였으며 이들 분포의 적합도를 PPCC Test를 사용하여 평가해봄으로써 낙동강 유역에서의 저수시의 유출량 추정에 대한 Power 분포의 적용성을 판단해 보았다. 뿐만 아니라 이와 관련된 수문요소기술을 확보할 수 있을 것이다.역의 물순환 과정을 보다 명확히 규명하고자 노력하였다.으로 추정되었다.면으로의 월류량을 산정하고 유입된 지표유량에 대해서 배수시스템에서의 흐름해석을 수행하였다. 그리고, 침수해석을 위해서는 2차원 침수해석을 위한 DEM기반 침수해석모형을 개발하였고, 건물의 영향을 고려할 수 있도록 구성하였다. 본 연구결과 지표류 유출 해석의 물리적 특성을 잘 반영하며, 도시지역의 복잡한 배수시스템 해석모형과 지표범람 모형을 통합한 모형 개발로 인해 더욱 정교한 도시지역에서의 홍수 범람 해석을 실시할 수 있을 것으로 판단된다. 본 모형의 개발로 침수상황의 시간별 진행과정을 분석함으로써 도시홍수에 대한 침수위험 지점 파악 및 주민대피지도 구축 등에 활용될 수 있을 것으로 판단된다. 있을 것으로 판단되었다.4일간의 기상변화가 자발성 기흉 발생에 영향을 미친다고 추론할 수 있었다. 향후 본 연구에서 추론된 기상변화와 기흉 발생과의 인과관계를 확인하고 좀 더 구체화하기 위한 연구가 필요할 것이다.게 이루어질 수 있을 것으로 기대된다.는 초과수익률이 상승하지만, 이후로는 감

• International conference on construction engineering and project management
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• 2009.05a
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• pp.30-31
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• 2009

Early detection of schedule delay in field construction activities is vital to project management. It provides the opportunity to initiate remedial actions and increases the chance of controlling such overruns or minimizing their impacts. This entails project managers to design, implement, and maintain a systematic approach for progress monitoring to promptly identify, process and communicate discrepancies between actual and as-planned performances as early as possible. Despite importance, systematic implementation of progress monitoring is challenging: (1) Current progress monitoring is time-consuming as it needs extensive as-planned and as-built data collection; (2) The excessive amount of work required to be performed may cause human-errors and reduce the quality of manually collected data and since only an approximate visual inspection is usually performed, makes the collected data subjective; (3) Existing methods of progress monitoring are also non-systematic and may also create a time-lag between the time progress is reported and the time progress is actually accomplished; (4) Progress reports are visually complex, and do not reflect spatial aspects of construction; and (5) Current reporting methods increase the time required to describe and explain progress in coordination meetings and in turn could delay the decision making process. In summary, with current methods, it may be not be easy to understand the progress situation clearly and quickly. To overcome such inefficiencies, this research focuses on exploring application of unsorted daily progress photograph logs - available on any construction site - as well as IFC-based 4D models for progress monitoring. Our approach is based on computing, from the images themselves, the photographer's locations and orientations, along with a sparse 3D geometric representation of the as-built scene using daily progress photographs and superimposition of the reconstructed scene over the as-planned 4D model. Within such an environment, progress photographs are registered in the virtual as-planned environment, allowing a large unstructured collection of daily construction images to be interactively explored. In addition, sparse reconstructed scenes superimposed over 4D models allow site images to be geo-registered with the as-planned components and consequently, a location-based image processing technique to be implemented and progress data to be extracted automatically. The result of progress comparison study between as-planned and as-built performances can subsequently be visualized in the D4AR - 4D Augmented Reality - environment using a traffic light metaphor. In such an environment, project participants would be able to: 1) use the 4D as-planned model as a baseline for progress monitoring, compare it to daily construction photographs and study workspace logistics; 2) interactively and remotely explore registered construction photographs in a 3D environment; 3) analyze registered images and quantify as-built progress; 4) measure discrepancies between as-planned and as-built performances; and 5) visually represent progress discrepancies through superimposition of 4D as-planned models over progress photographs, make control decisions and effectively communicate those with project participants. We present our preliminary results on two ongoing construction projects and discuss implementation, perceived benefits and future potential enhancement of this new technology in construction, in all fronts of automatic data collection, processing and communication.