• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.130-130
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• 2022

기후변화로 인한 기상이변 현상으로 폭우와 홍수 등 수문학적 극치 사상의 출현 빈도가 잦아지고 있다. 따라서 이러한 기상이변 현상에 적응하기 위하여 보다 정확한 확률강우량 측정의 필요성이 증가하고 있다. 대장 지점의 미래 확률강우량 계산을 위해선 기후변화 시나리오의 비정상성을 고려해야 한다. 본 연구는 비정상적인 미래 기후에서 확률강우량이 어떻게 변화하는지 측정하는 것을 목표로 한다. Representative Concentration Pathway (RCP4.5)에 따른 우리나라의 확률강우량 계산에 인공신경망을 포함한 정상성, 비정상성 확률강우량 산정 모델들이 사용되었다. 지점빈도해석(AFA), 홍수지수법(IFM), 모분포홍수지수법(PIF), 인공신경망을 이용한 Quantile & Parameter regression technique(QRT & PRT)이 정상성 자료에 대해 확률강우량을 계산하는 모델로 사용되었으며, 비정상성 자료에 대해서는 비정상성 지점빈도해석(NS-AFA), 비정상성 홍수지수법(NS-IFM), 비정상성 모분포홍수지수법(NS-PIF), 인공신경망을 사용한 비정상성 Quantile & Parameter regression technique(NS-QRT & NS-PRT)이 사용되었다. Rescaled Akaike information criterion(rAIC)를 사용한 불확실성 분석과 적합도 검정을 통해서 generalized extreme value(GEV) 분포형 모델이 정상성 및 비정상성 확률강우량 산정에 가장 적합한 모델로 선정되었다. 이후, 관측자료가 GEV(0,0,0)을 따르고 시나리오 자료가 GEV(1,0,0)을 따르는 지점들을 선택하여 미래의 확률강우량 변화를 추정하였다. 각 빈도해석 모델들은 몬테카를로 시뮬레이션을 통해 bias, relative bias(Rbias), root mean square error(RMSE), relative root mean square error(RRMSE)를 바탕으로 측정하여 정확도를 계산하였으며 그 결과 QRT와 NS-QRT가 각각 정상성과 비정상성 자료로부터 가장 정확하게 확률강우량을 계산하였다. 본 연구를 통해 향후 기후변화의 영향으로 확률강우량이 증가할 것으로 예상되며, 비정상성을 고려한 빈도분석 또한 필요함을 제안하였다.

• The Journal of the Korea Contents Association
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• v.22 no.6
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• pp.369-385
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• 2022

This thesis was a phenomenological study of an after-school picture book making program for middle school students. This study attempted to establish a theoretical system for picture book making activity by analyzing the process of self-discovery and healing through the picture book making activity. The participants were six middle school students, the picture book making activity program was organized into five stages, and in-depth interviews of the study participants and their interpretation of picture books were described. According to the research results, first, the making activity of picturebooks can construct one's own world through hyper-reality that is more excessive than the original. Second, it can be said that the fearful existence of a monster has developed awareness and insight to view its own problems from various angles through defamiliarization. These results might be that the making activity of picturebooks is a way of revealing one's existence to the world, and through this, the process of exploring and constructing the meaning of oneself and daily life. Discussion was made based on this about the creation of another world where the picturebook making activity is different from the original, the stimulating effect of the subconscious mind through the defamiliarization device, and the establishment of self-existence in picturebook creation.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.6
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• pp.1465-1477
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• 1993

Powder Injection Molding(PM) is an advanced and complicated technology for manufacturing ceramic or metal products making use of a conventional injection molding process, which is generally used for plastic products. Among many technologies involved in the successful PIM, injection molding process is one of the key steps to form a desired shape out of powder/binder mixtures. Thus, it is of great importance to have a numerical tool to predict the powder injection molding filling process. In this regard, a finite element analysis system has been developed for numerical simulations of filling process of powder injection molding. Powder/polymer mixtures during the filling pro cess of injection molding can be rheologically characterized as Non-Newtonian fluids with a so called yield phenomena and have a peculiar feature of apparent slip phenomena on the wall boundaries surrounding mold cavity. Therefore, in the present study, a physical modeling of the filling process of powder/polymer mixtures was developed to take into account both the yield stress and slip phenomena and a finite element formulation was developed accordingly. The numerical analysis scheme for filling simulation is accomplished by combining a finite element method with control volume technique to simulate the movement of flow front and a finite difference method to calculate the temperature distribution. The present study presents the modeling, numerical scheme and some numerical analysis results showing the effect of the yield stress and slip phenomena.

• Journal of the Korean Geophysical Society
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• v.4 no.1
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• pp.1-10
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• 2001

A number of tangible cultural properties have been left to suffering damage without any scientific conservation or maintenance. We conducted nondestructive geophysical explorations around the Western pagoda of the Iksan Mireuksa Temple for the purpose of preparing the counterplan of its conservation and maintenance and of utilizing the geophysical information for the design of repair. Geophysical image of the shallow subsurface around the construct resulting from electric resistivity, seismic refraction, and GPR methods carried out along 6 lines in the site was used to investigate the relationship between the foundation characteristics and the structural safety. Tilting of the pagoda southwest towards seems to result from the low resistivity zones found in the southwestern part. The GPR and seismic surveys revealed a boundary at depth of 3.3～3.5m dividing into two layers, compacted overlaid soil and the original ground. The boundary appears to dip southwest. The artificial layer as a foundation does not covers as much as the bottom area of the pagoda. This top soil dipping southwest seems to result in tilting of foundation southwestward towards. Our geophysical result suggests ground reinforcement in the western part of the survey area for the conservation of the construct.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.4
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• pp.84-91
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• 2002

Thrust vector characteristics of jet vanes installed in a shroud are very unique and much more complicated than those of the jet vane acting without any shroud by the fact of additional physical phenomena. The fluid dynamic interferences induced by jet vanes and shroud as well as jet vane's aerodynamic performance are investigated to characterize thrust vector control by semi-empirical model, three dimensional numerical analysis including real complex geometry, and ground firing test of real motors.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.748-751
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• 2014

This paper has analyzed threshold voltage movement for channel doping concentration of asymmetric double gate(DG) MOSFET. The asymmetric DGMOSFET is generally fabricated with low doping channel and fully depleted under operation. Since impurity scattering is lessened, asymmetric DGMOSFET has the adventage that high speed operation is possible. The threshold voltage movement, one of short channel effects necessarily occurred in fine devices, is investigated for the change of channel doping concentration in asymmetric DGMOSFET. The analytical potential distribution of series form is derived from Possion's equation to obtain threshold voltage. The movement of threshold voltage is investigated for channel doping concentration with parameters of channel length, channel thickness, oxide thickness, and doping profiles. As a result, threshold voltage increases with increase of doping concentration, and that decreases with decrease of channel length. Threshold voltage increases with decrease of channel thickness and bottom gate voltage. Lastly threshold voltage increases with decrease of oxide thickness.

• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.3 s.55
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• pp.164-172
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• 2009

Anchors and saddles are used to have sufficient geometrical rigidity and make target configuration of main cable of suspension bridge. Neglecting the sliding effect at saddles, points at them have been idealized as fixed nodes in lots of former studies. In general, sliding effects are reported to show significant structural behaviors of main cable and cause to the different responses of bridges. During early erection steps of the suspension bridge, especially, the sliding effect occurs easily because there is large difference of cable tension between main and side span in removing set-back ropes or not applying set-back. This study presents the finite element analysis considering to cable sliding effect and shows the comparison of differences between sliding and non-sliding at election sequence. The analysis of sliding between main cables and saddles needs to obtain more realistic responses because the analysis result can represent unfavorably different responses of bridges. Moreover, the sliding analysis method and results in this study can be used to basic criteria in engineering design and construction steps.

• Journal of Korea Soil Environment Society
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• v.1 no.2
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• pp.91-101
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• 1996

In recent years, phytoremediation, the use of plants to detoxify hydrocarbons, has been a promising new area of research, particularly in situ cleanup of large volumes of slightly contaminated soils. There is increasing need for a mathematical model that can be used as a predictive tool prior to actual field implementation of such a relatively new technique. Although a number of models exist for solute-plant interaction in the vegetated zone of soil, most of them have focused on ionic nutrients and some metals. In this study, we developed a mathematical model for simulation of bioremediation of hydrocarbons in soil, associated with plant root systems. The proposed model includes root interactions with soil-water and hydrocarbons in time and space, as well as advective and dispersive transport in unsaturated soil. The developed model considers gas phase diffusion and liquid-gas mass exchanges. For simulation of temporal and spatial changes in root behavior on soil-water and with hydrocarbons, time-specific distribution of root quantity through soil was incorporated into the simulation model. Hydrocarbon absorption and subsequent uptake into roots with water were simulated with empirical equations. In addition, microbial activity in the rhizosphere, a zone of unique interaction between roots and soil microorganisms, was modeled using a biofilm theory. This mathematical model for understanding and predicting fate and transport of compound in plant-aided remediation will assist effective application of plant-aided remediation to field contamination.

• Journal of the Korean Geophysical Society
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• v.4 no.2
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• pp.103-111
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• 2001

Geophysical survey was carried out to derive some information on the existence of near-surface anomalous body at Reung-Chi area in Kongju. Resistivity, seismic, magnetic and gravity method were applied. Geophysical survey that was applied was the electrical resistivity survey, seismic survey, magnetic survey, gravity survey. These surveys are analyzed to provide data of high resolution. As a result of analysis of resistivity survey, anomalies showing high resistivity anomaly than around appeared, and the one showing M-shape out of those explains the possibility that underground common or other underground structure or geographical anomalous zone could exist in the underground. As a result of analysis of seismic survey, it is clear that the low velocity layer is spread as far as the bottom of the underground. It is possible to presume that it is a phenomenon appearing while going through the underground space where it is lying in the underground. Area that shows unusual situation in interpretation of data on seismic waves are included into the area that once showed resistivity anomaly, the results of both seismic surveys come in accord. As a result of magnetic survey, a circle-shape of twin magnetic fields in the area where abnormalities are shown between electrical resistivity survey and seismic survey is appeared. Given the area of gravity survey, abnormalities whose density is different from the one around the bottom of the underground. As a result of analogizing the data of underground of the subsurface based on analysis of data from each survey, it was interpreted that anomalous zone exists commonly in the research areas.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.14-14
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• 2018

세계의 여러 국가에서 과거 발생했던 강수의 통계적 특성에서 벗어나는 극치사상이 빈번하게 관측되고 있다. 이와 같은 현상에 가장 큰 영향을 미치고 있는 요인중 하나는 지구온난화이며 실제 산업화 이후 온실가스의 증가와 더불어 극한 기상현상의 발생 빈도가 증가하였다. 현재 예상치 못한 수문사상의 발생으로 인해 수자원관리에 있어서 많은 어려움을 겪고 있으며, 특히 호우사상은 막대한 인명 및 사회적 피해를 야기하고 있다. 우리나라의 경우 계절적 특징으로 여름철에 강수가 집중되는 양상을 보이고 있으며 따라서 여름철 강수량을 예측하여 호우에 대한 대비책을 마련해야한다. 계절강수 예측은 수문, 산림, 식품, 등을 포함한 사회 경제적 파급 효과가 매우 크지만 아직 신뢰성 있는 예측은 어려운 상태이다. 또한, 발생 강도와 빈도가 큰 극한 강우는 주로 짧은 시간에 걸쳐 발생하기 때문에 예측하기가 어렵다. 최근 다양한 분야의 연구에서 AO, NAO, ENSO, PDO등과 같은 외부적 요인이 수문학적 빈도를 변화시킨다고 알려지고 있어 본 연구에서는 Bayesian 통계기법을 이용한 비정상성 빈도해석모형을 토대로 외부 기상인자에 의한 변동성을 고려할 수 있는 계절강수량 예측모형을 구축한 후 산정된 결과를 입력 자료로 하여 극치강수량을 추정할 수 있는 비정상성 Four - Parameter (4P)-Beta분포를 이용한 알고리즘을 개발하여 직접적으로 일단위 이하의 극치강수량을 상세화 시킬 수 있는 모형으로 확장하여 이를 통해 기상변동성을 다양한 시간규모에서 고려하기 위한 정보로 활용하고자 하였다.