• 한국시뮬레이션학회논문지
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• 제25권3호
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• pp.117-123
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• 2016

본 연구는 다중서버 대기행렬시스템의 관측이 제한되어 있는 경우에 시스템 내부 행태를 추론하는 데에 그 목적이 있다. 대기행렬시스템 분석에 있어 도착 및 서비스시간에 자기상관성이 존재하면 이론적으로 모형화하기가 매우 복잡하고 어렵다. 이에 따라 다양한 분석 기법 및 확률과정 모형들이 개발되었다. 본 논문에서는 외부 관측치에 존재하는 자기상관성과 내부 행태를 관측하기 어려운 경우에 대한 추론 방법을 소개한다. 선행연구의 가정을 완화하여 추론 방법을 제시하고 그에 대한 보조정리 및 정리를 제시한다. 제시된 비모수적 방법을 적용하면 서비스시간에 자기상관성이 존재하더라도 외부 관측치만을 사용하여 다중서버 대기행렬의 내부 행태를 추론할 수 있다. 주요 내부 추론 결과로는 대기시간과 서비스시간을 사용하였다. 또한 제시된 방법의 타당성 검증을 위해 실험 결과를 제시하였다.

• 한국BIM학회 논문집
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• 제13권4호
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• pp.96-105
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• 2023

This study focuses on developing a building object recognition technology for efficient use in the remodeling of buildings constructed without drawings. In the era of the 4th industrial revolution, smart technologies are being developed. This research contributes to the architectural field by introducing a deep learning-based method for automatic object classification and recognition, utilizing point cloud data. We use a TD3D network with voxels, optimizing its performance through adjustments in voxel size and number of blocks. This technology enables the classification of building objects such as walls, floors, and roofs from 3D scanning data, labeling them in polygonal forms to minimize boundary ambiguities. However, challenges in object boundary classifications were observed. The model facilitates the automatic classification of non-building objects, thereby reducing manual effort in data matching processes. It also distinguishes between elements to be demolished or retained during remodeling. The study minimized data set loss space by labeling using the extremities of the x, y, and z coordinates. The research aims to enhance the efficiency of building object classification and improve the quality of architectural plans by reducing manpower and time during remodeling. The study aligns with its goal of developing an efficient classification technology. Future work can extend to creating classified objects using parametric tools with polygon-labeled datasets, offering meaningful numerical analysis for remodeling processes. Continued research in this direction is anticipated to significantly advance the efficiency of building remodeling techniques.

• Structural Engineering and Mechanics
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• 제90권4호
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• pp.371-390
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• 2024

Investigating the impact of openings on the structural behavior of ferrocement I-beams with two distinct types of reinforcing metallic and non-metallic meshes is the primary goal of the current study. Up until failure, eight 250x200x2200 mm reinforced concrete I-beams were tested under flexural loadings. Depending on the kind of meshes used for reinforcement, the beams are split into two series. A control I-beam with no openings and three beams with one, two, and three openings, respectively, are found in each series. The two series are reinforced with three layers of welded steel meshes and two layers of tensar meshes, respectively, in order to maintain a constant reinforcement ratio. Structural parameters of investigated beams, including first crack, ultimate load, deflection, ductility index, energy absorption, strain characteristics, crack pattern, and failure mode were reported. The number of mesh layers, the volume fraction of reinforcement, and the kind of reinforcing materials are the primary factors that vary. This article presents the outcomes of a study that examined the experimental and numerical performance of ferrocement reinforced concrete I-beams with and without openings reinforced with welded steel mesh and tensar mesh separately. Utilizing ANSYS-16.0 software, nonlinear finite element analysis (NLFEA) was applied to illustrate how composite RC I-beams with openings behaved. In addition, a parametric study is conducted to explore the variables that can most significantly impact the mechanical behavior of the proposed model, such as the number of openings. The FE simulations produced an acceptable degree of experimental value estimation, as demonstrated by the obtained experimental and numerical results. It is also noteworthy to demonstrate that the strength gained by specimens without openings reinforced with tensar meshes was, on average, 22% less than that of specimens reinforced with welded steel meshes. For specimens with openings, this value is become on average 10%.

• Structural Engineering and Mechanics
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• 제90권6호
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• pp.611-633
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• 2024

This study intends to investigate the response of multi-cell (MC) beams to flexural loads in which the primary reinforcement is composed of both metallic and non-metallic materials. "Multi-cell" describes beam sections with multiple longitudinal voids separated by thin webs. Seven reinforced concrete MC beams measuring 300×200×1800 mm were tested under flexural loadings until failure. Two series of beams are formed, depending on the type of main reinforcement that is being used. A control RC beam with no openings and six MC beams are found in these two series. Series one and two are reinforced with metallic and non-metallic main reinforcement, respectively, in order to maintain a constant reinforcement ratio. The first crack, ultimate load, deflection, ductility index, energy absorption, strain characteristics, crack pattern, and failure mode were among the structural parameters of the beams under investigation that were documented. The primary variables that vary are the kind of reinforcing materials that are utilized, as well as the kind and quantity of mesh layers. The outcomes of this study that looked at the experimental and numerical performance of ferrocement reinforced concrete MC beams are presented in this article. Nonlinear finite element analysis (NLFEA) was performed with ANSYS-16.0 software to demonstrate the behavior of composite MC beams with holes. A parametric study is also carried out to investigate the factors, such as opening size, that can most strongly affect the mechanical behavior of the suggested model. The experimental and numerical results obtained demonstrate that the FE simulations generated an acceptable degree of experimental value estimation. It's also important to demonstrate that, when compared to the control beam, the MC beam reinforced with geogrid mesh (MCGB) decreases its strength capacity by a maximum of 73.33%. In contrast, the minimum strength reduction value of 16.71% is observed in the MC beams reinforced with carbon reinforcing bars (MCCR). The findings of the experiments on MC beams with openings demonstrate that the presence of openings has a significant impact on the behavior of the beams, as there is a decrease in both the ultimate load and maximum deflection.

• 사회복지연구
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• 제41권1호
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• pp.119-144
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• 2010

본 연구는 비행친구와 비행 간의 관계가 종단적으로 역동적일 뿐만 아니라 그 관계성에 다양한 잠재적 유형이 있을 수 있음을 밝히고자 한다. 청소년패널자료를 활용하여 분석한 결과, 비행친구 발달궤적은 중2에서 고2까지 4회기 동안 비행친구가 없는 집단, 비행친구가 감소하는 집단, 비행친구가 지속되는 집단 세 가지 유형으로 구분되었다. 비행친구 발달궤적과 비행 발달궤적 간의 종단적인 역동적 관계를 살펴본 결과, 비행친구 발달궤적 집단 중 비행집단이 될 확률은 비행친구 지속형 집단이 가장 높고, 비행친구 억제형 집단이 가장 낮은 것으로 나타나 비행친구의 영향효과를 확인할 수 있었다. 비행친구 지속형 집단은 만성형 비행집단이 될 확률이 가장 높은 것으로 나타나 비행친구의 상승효과를 보여주고 있다. 반면 비행친구 감소형 집단은 저비행지속형 집단이 될 확률이 가장 높았고, 비행친구 지속형 집단은 중단형 비행집단이 될 확률이 가장 높은 것으로 나타났다. 이러한 결과는 비행친구의 선택효과를 반증하는 것이다. 본 연구결과는 비행친구의 영향효과, 선택효과, 상승효과를 동시에 지지하는 것으로서, 이러한 여러 가지 설명이 동등하게 타당하며 비행친구와 비행 간의 관계는 종단적으로 상호적이며 역동적인 관계로 이해되어야 함을 보여주고 있다.

• 한국농공학회논문집
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• 제62권5호
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• pp.47-62
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• 2020

Rice paddy accounts for approximately 52.5% of all farmlands in South Korea, and it is closely related to the water environment. Climate change is expected to affect not only agricultural productivity also the water and the nutrient circulation. Therefore this study was aimed to evaluate changes of nitrogen load from rice paddy considering climate change scenario uncertainty. APEX-Paddy model which reflect rice paddy environment by modifying APEX (Agricultural Policy and Environmental eXtender) model was used. Using the AIMS (APCC Integrated Modeling Solution) offered by the APEC Climate Center, bias correction was conducted for 9 GCMs using non-parametric quantile mapping. Bias corrected climate change scenarios were applied to the APEX-Paddy model. The changes and uncertainty in runoff and nitrogen load were evaluated using multi-model ensemble. Paddy runoff showed a change of 23.1% for RCP4.5 scenario and 45.5% for RCP8.5 scenario compared the 2085s (2071 to 2100) against the base period (1976 to 2005). The nitrogen load was found to be increased as 43.9% for RCP4.5 scenario and 76.0% for RCP8.5 scenario. The uncertainty analysis showed that the annual standard deviation of nitrogen loads increased in the future, and the maximum entropy indicated an increasing tendency. And Duncan's analysis showed significant differences among GCMs as the future progressed. The result of this study seems to be used as a basis for mid- and long-term policies for water resources and water system environment considering climate change.

• 대한환경공학회지
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• 제32권2호
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• pp.165-174
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• 2010

석탄 가스화 반응을 모델링하여 습식분류층 석탄 가스화기의 반응특성에 대한 수치해석적 연구를 수행하였다. 본 연구의 목적은 신뢰성 있는 수치해석기술을 이용하여 가스화 장치의 기본설계와 더불어 최적 운전조건의 설정에 있다. 석탄 가스화 반응은 복사가 관여하는 고체와 기체의 이상 난류반응으로서 수증기 증발로부터 휘발화, 촤와 가스의 반응 등 일련의 연소반응의 구조를 가진다. 본 연구에서는 실험과 수치해석적인 방법을 병행하여 연구를 수행하였으며 한국에너지기술연구원에 설치된 1톤 규모의 실험용 가스화기를 대상으로 하였다. 본 연구에서는 기본적으로 상용프로그램을 사용하였으며 석탄 가스화 반응해석에 필요한 여러 서브루틴을 개발하여 해석하였다. 세부 반응 서브루틴의 난류반응은 기본적으로 에디붕괴모델에서 화학적 반응속도의 개념을 조화평균의 형태로 사용하였다. 그리고 석탄입자궤적은 라그란지안 접근방식을 선택하였으며 입자의 궤적 계산에서 저항력에 나타나는 난류비선형적인 문제에 대한 모델도 고려하였다. 이와 같이 개발된 프로그램은 실험에서 얻어진 가스농도와 온도분포 그리고 냉가스 효율 등의 자료들과 비교하여 성능을 일차적으로 검토하였다. 석탄의 입자크기분포, 석탄 슬러리 농도, 그리고 가스화기의 형상변화는 가스화 성능에 직접적으로 영향을 주며 이를 합성가스 생성량과 냉가스 효율을 통해 비교 검토하였다. 본 연구 결과가 비록 물리적으로 타당하고 변수연구의 일관성을 보여주나 기류층 석탄가스화 반응장치의 복잡성을 고려하여 볼 때 보다 많은 실험결과에 대한 정교한 모델검증 노력이 신뢰성 있는 프로그램의 완성에 필요할 것으로 판단된다.