• Journal of the Earthquake Engineering Society of Korea
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• v.6 no.3
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• pp.53-62
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• 2002

Site soil condition affects significantly on the seismic response of a structure and is a critical factor for the performance based seismic design of a structure. In this paper, the effects of nonlinear soil properties on the elastic response spectra of a structure including the nonlinearity of a soil due to the earthquake excitation is investigated using one step finite element approach for the entire soil structure system and approximate linear iterative procedure to simulate the nonlinear soil behavior with the Ramberg-Osgood soil model. Studies were carried out for a linear SDOF system of a variable period with and without a pile group for the 1940 CI Centro earthquake recorded on ground rather than rock. The study results showed clearly that the effect of the nonlinear behavior of soft soil is very important on the elastic seismic response of a structure suggesting the necessity of the performance based seismic design.

• Journal of the Earthquake Engineering Society of Korea
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• v.6 no.6
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• pp.7-15
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• 2002

In this paper, the nonlinear parameter estimation method using the estimated hysteresis of each structural members was studied for the purpose of efficient seismic damage prediction and estimation of MDOF nonlinear structural model in the shaking table test. The hysteresis of each structural members can be obtained by the conversion of measured response histories into relative motions of each structural members and member forces. These hysteresis can be used to evaluate various kinds of damage indices of each structural members. The MDOF nonlinear structural model for further analysis(re-analysis) can be easily reconstructed using estimated nonlinear structural parameters of each structural members. To demonstrate the proposed techniques, several numerical and experimental example analyses are carried out. The results indicate that the proposed method can be very useful to assess local seismic damages of structures.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.623-627
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• 2005

유역의 유출특성을 정확히 분석하기 위해서는 모형에 내재된 매개변수의 적정한 추정이 필수적이나 정확한 측정이 불가능한 변수들의 최적해를 결정하는 것은 어려운 일이다. 본 연구에서는 괴산댐유역을 적용대상 유역으로 PRMS 모형의 최적 매개변수를 평가하고, 추정난해 매개변수 9개에 대한 민감도 분석을 수행함으로서 각 매개변수에 따른 결과의 불확실성과 유출특성에 미치는 영향을 분석하여 향후 정도 높은 매개변수 추정에 활용하고자 하였다. 연구결과 지표면유출 관련인자는 지표면-지표하유출량을 변화시키므로 유출특성에 큰 영향을 미치는 것으로 나타났다. 또한 지표하유출 관련 매개변수들은 비선형계수가 작아져 유출이 선형적으로 고려될 때 수문곡선에 영향을 주는 것으로 판명되었다. 한편 지하수유출 관련 계수는 지하수유출이 발생하는 경우 영향을 미치지 않는 것으로 나타났고, 지표하저수지에서 지하수유출을 발생시키는 매개변수는 크게 민감하지 않은 것으로 판명되었다. 그리고 토양대에서 지하수저수지로의 유입 관련 매개변수는 유출을 지연시키는 효과를 보였고 증발산을 조절하는 매개변수는 유출용적에만 영향을 미치는 것으로 판명되었다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.3
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• pp.106-115
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• 2011

This study proposed a new methodology for seismic capacity evaluation of low-rise reinforced concrete (RC) buildings based on non-linear required spectrum. In order to verify the reliability of the proposed method, relationships between results obtained using the proposed method and the non-linear dynamic analyses were investigated. Compared with the seismic protection index (Es=0.6) defined in the Japanese Standard, the applicability of the method was also estimated. Research results indicate that the method proposed in this study compares reasonably well with the detailed evaluation methods. Using the seismic evaluation method developed in this study, the seismic capacity category and earthquake damage degree of low-rise RC buildings corresponding to a specific earthquake level can be effectively estimated.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.33 no.3
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• pp.226-233
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• 1997

예망어구의 유체역학적인 특성과 예망어구내에서의 유속 측정 자료를 기초로 어류의 측선 유수감각에 작용하는 유효한 유수자극량을 추산하고 정량화하기 위하여 예망어구내의 3차원적인 상대유속의 선형적인 분포정도를 모델링하였다. 예망어구내의 상대유속은 망지의 제반규격과 예망어구의 수중 전개형상에서의 각부 거리비에 따라 상대유속비를 선형적으로 수식화하여 본문의 식(3)과 (8)로 표현하였다. 이러한 상대유속비는 어류의 측선 유수감각기관에 의하여 탐지될 수 있는 와동 유수자극량의 지표로써 사용될 수 있다. 어류의 유수감각 예민도는 어류의 전장과 어체주위 상대유속에 의하여 선형적으로 변화되는 것으로 가정하고 본문의 식(9)와 같이 탐지가능한 상대유속차의 최소값으로 나타내었다. 예망어구내의 상대유속 분포에 관한 본 모델의 계산 결과는 실물예망어구에서 실측된 상대유속의 범위내에서 거의 근사하게 나타났으며 본 모델은 어류의 대망행동 모델링에서 예망어구의 유수자극과 어류의 유수감각 예민도를 상대적으로 정량화하여 어류행동의 반응요인으로 적용할 수 있을 것이다.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1306-1317
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• 2008

최근 용지보상이나 환경문제 및 도로선형 등으로 인해 도로건설 중 터널구간이 늘어나고 있으며, 이로 인해 터널시공 중 크고 작은 붕괴 및 이에 대한 보강이 빈번히 발생하고 있다. 대부분의 터널이 지표하 수십 m에서 깊게는 100m 이상에서 건설되고 있어 지표에서 붕괴의 원인 및 보강결과에 대한 확인이 결코 쉽지만은 않은 상황이다. 본 사례에서는 지표하 약 130m에 위치한 터널붕락 구간에 대하여 터널내에서 비파괴검사인 3차원 전기비저항탐사를 실시하여 보강결과를 확인하였다.

• 한국공간정보시스템학회:학술대회논문집
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• 2005.11a
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• pp.35-39
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• 2005

선형혼합분광분석(LSU, Linear Spectral Unmixing) 모델은 위성 영상의 한 화소 값이 공간 내에 포함된 다양한 지표 대상물의 반사에너지가 혼합된 결과로 나타난다는 가정을 통해 화소이하(Sub-Pixel) 단위의 영상 분석을 수행하는 알고리즘의 한 형태이다. 분석의 결과는 한 화소에 존재하는 순수 대상물(Endmember)의 비율로 나타나며, 최소제곱법을 이용하여 결과를 도출하는 것이 일반적인 방법으로 알려져 있다. 하지만, 최소제곱법을 이용한 선형혼합분광분석모델은 기본적인 가정을 만족시키지 못하며, Endmember를 사용자가 임의로 지정해야 하기 때문에 영상 분석에 많은 어려움이 있다. 이런 단점을 극복하기 위해 무감독으로 추출된 Endmember를 이용한 제약선형분광혼합분석(Constrained Linear Spectral Unmixing) 모델을 본 연구를 통해 제안하고자 한다. 결과를 통해, 무감독 제약선형분광혼합분석 모델은 선형분광혼합분석 모델에 비해 각각의 Endmember에 대하여 제약조건을 만족하는 점유비율(Abundance) 정보를 제공하였으나, 비슷한 Endmember를 중복 추출할 수 있는 가능성도 지니고 있음을 확인할 수 있었다.

• Explosives and Blasting
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• v.38 no.4
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• pp.26-36
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• 2020

With the increase of expansion and use of the underground space, the possibility of an underground explosion by terrorists is increasing. In this study, after modeling a circular tunnel excavated at a depth of 50m, an explosion load was applied to the inside of the tunnel. As for the explosion load, the explosion load of the maximum explosive amount for six types of vehicle booms proposed by ATF (Bureau of Alcohol, Tobacco, and Firearms) was calculated. For the rock mass around the circular tunnel, three types of rock grades were selected according to the support pattern suggested in the domestic tunnel design. Nonlinear dynamic analysis was performed to evaluate the influence of the ground structure by examining the surface displacement using the explosion load and rock mass characteristics as parameters. As a result of the analysis, for grade 1 rock, the influence on the uplift of the surface should be considered, and for grade 2 and 3 rocks, the influence on a differential settlement should be considered. In particular, for grade 3 rocks, detailed analysis is required for ground-structure interaction within 40m. Also, it is considered that the influence of Young's modulus is the main factor for the surface displacement.

• The Transactions of the Korea Information Processing Society
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• v.13 no.8
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• pp.388-394
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• 2024

Since recommendation systems play a key role in increasing the revenue of companies, various approaches and models have been studied in the past. However, this diversity also leads to a complexity in the types of recommendation systems, which makes it difficult to select a recommendation model. Therefore, this study aims to solve the difficulty of selecting an appropriate recommendation model for recommendation systems by providing a unified criterion for categorizing various recommendation models and comparing their performance in a unified environment. The experiments utilized MovieLens and Coursera datasets, and the performance of linear models(ADMM-SLIM, EASER, LightGCN) and non-linear models(Caser, BERT4Rec) were evaluated using HR@10 and NDCG@10 metrics. This study will provide researchers and practitioners with useful information for selecting the best model based on dataset characteristics and recommendation context.

• The Korean Journal of Quaternary Research
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• v.24 no.2
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• pp.1-11
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• 2010

Energy Balance Model (EBM) was used to experiment the distribution of surface equilibrium temperature which responds to external forcing associated with the surface characteristics. Surface equilibrium temperature is calculated as sum of incoming solar radiation and latitudinal transport is balanced with outgoing infrared radiation. To treat incoming solar radiation, the source of the earth energy, significantly for energy balance, the experiment for surface equilibrium temperature distribution was performed considering the energy balance with the latitudinal albedo change as well as land and sea distribution. In addition, linear albedo change experiment, arctic albedo 5%, 10%, 15% change experiments and the opposite albedo change experiments between arctic and mid-latitudes were performed using incoming solar radiation as an external forcing. Moreover, with and without ice-albedo feedback experiments were performed. Increasing of arctic albedo is blocked out the incoming solar radiation so that it induces decreasing of latitudinal heat transport. It is strengthened energy transport from low latitudes by keeping arctic low energy states. Therefore the temperature change in the mid-latitudes exhibits larger response than that of arctic due to the difference of transport. The land which has lower heat capacity than sea can be reach to equilibrium temperature shortly. Also land is more sensitive to temperature change with respects to albedo. Thus it induces the thermal difference between land and sea. As a result, the equilibrium temperature exhibits differently as the difference of albedo and heat capacity which are the one of surface characteristics. Surface equilibrium temperature decreases as albedo increase and the ratio of temperature change is large as heat capacity is small. The decreasing of surface equilibrium temperature with respects to increasing of linear albedo is accelerated by ice-albedo feedback. However local change of surface equilibrium temperature decreases non-linearly.