• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2006년도 제26회 춘계학술대회논문집
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• pp.171-176
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• 2006

연료 과농 가스발생기에 대한 실험적 연구가 수행되었다. 연소 성능에 주요한 영향을 미치는 분사기 헤드에는 1.5의 리세스 수를 갖는 내부 혼합형 이중 스월 분사기 37개가 배치되었다. 본 논문에서는 연소실 길이, 직경, 그리고 교반링 등의 연소실 설계 변경에 따른 실물형 가스발생기의 연소 안정성 특성에 대하여 살펴보았다. 연소시험 결과 공진 주파수가 고주파 영역에서 생성됨에 따라 동압의 세기는 전반적으로 감소하였으나, 연소 불안정을 완전히 억제시키지는 못하는 것으로 나타났다.

• 한국해양공학회지
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• 제12권3호통권29호
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• pp.86-95
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• 1998

CAD/CAM program developers have made substantial progress in enabling engineers to design, analyze, visualize, visualize, and simulate the performance of structures and systems. Many researchers, however, agree that there is still a way to go before the existing commercial computer software can be used in ship structural analysis to their full potential as solvers which can identify opportunities to reduce man-hours and cut costs. CAD systems used for these works in ship yards are general-purposed and not custom-tailored for ship structures, which force end-users to do tiresome and routine works. The new preprocessor "MeshGen" announced in this study can load several ship types and user-friendly generate their FE meshes employing the object-oriented approach based on the parametric and top-down design. Also "MeshGen" reduces dramatically the time required to prepare CAD models under window-based environments on desktop personal computers and makes it much easier and faster for end-users to change topology and material properties.

• Journal of Advanced Research in Ocean Engineering
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• 제4권2호
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• pp.66-77
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• 2018

This paper presents a parametric study on an oscillating water column (OWC) wave energy converter (WEC). This OWC has been planned for installation in the breakwaters on isolated islands located away from the mainland. Both a numerical analysis and a model experiment are utilized for determining a proper conceptual design for this purpose. Various design parameters, including the configurations and dimensions, are evaluated through the numerical analysis, which is based on a potential flow theory, and several design concepts are then selected as candidates. The model experiment using a 2D wave flume is conducted to evaluate the effects of the design parameters and compare the performances of the candidates. Based on the overall results of the numerical analysis and model experiment, a conceptual design of the OWC WEC applicable to a breakwater is selected.

• 대한기계학회논문집B
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• 제27권5호
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• pp.635-643
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• 2003

Parametric study for the analysis of performance characteristics of a planar -type solid oxide fuel cell(SOFC) using computational flow analysis is conducted. A planar -type SOFC, which is composed by two gas channels (fuel and ai.) and one set of anode-electrolyte-cathode assembly, is modeled as a two -dimensional isothermal case. Results of computational analysis of flow field including distributions of mass fractions in gas channels are used to the performance analysis of the fuel cell. Flow analysis makes it possible to consider current density distributions along the length of the cell in the process of performance analysis of the SOFC. As results of parametric study, it is found that the mole fraction of fuel at the inlet of fuel channel, operating pressure and temperature are closely related to the performance characteristics of SOFC.

• Geomechanics and Engineering
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• 제15권4호
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• pp.973-986
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• 2018

The objective of this paper is to present abacuses obtained from a parametric study of deep-lined tunnels using a numerical finite element model. This numerical model was implemented in software GEOMEC91, which is a two-dimensional axisymmetric model that considers the progress of excavation and the placing of the lining through the activation and deactivation of elements. It is adopted a step of excavation constant (1/3 of radius), constant velocity and circular cross section along the tunnel axis. It is used for rock mass a viscoplastic constitutive law with von-Mises criterion of viscoplasticity without hardening whose deformation rate over time is given by the Bingham model. The lining uses a linear elastic constitutive law. In total are 1716 analysis presented in 60 abacuses that show the value of ultimate convergence ($U_{eq}$) due to tunneling speed. In addition, it is shown an example of the use of the abacuses to determine the ultimate convergence ($U_{eq}$) of the tunnel and pressure ($P_{eq}$) on the lining.

• 한국철도학회논문집
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• 제9권5호
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• pp.561-568
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• 2006

Dynamic equations of motion for the interaction system of bridge and vehicle are derived to investigate the dynamic responses of bridge and vehicles induced by moving automated guide-way transit(AGT) vehicle and surface roughness of bridge. The vehicle model for ACT vehicle is idealized as 11 DOF including yawing, lateral translation and steering of wheels, and the bridges are modeled with finite element method. The AGT vehicle model was verified by experimental study. Parametric studies are carried out to investigate the effect of vehicle speed, surface roughness, stiffness and damping of the suspension system, AGT vehicles and dynamic wheel loads of the AGT vehicles. From the parametric study it can be seen that the dynamic incremental factor of the bridge and dynamic responses of vehicles have a tendency to increase with vehicle speeds, surface roughness and the stiffness of AGT vehicle suspension system. On the other hand those dynamic wheel loads have tendencies to decrease in according to increase of damping of the suspension system.

• 한국철도학회논문집
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• 제13권5호
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• pp.516-520
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• 2010

튜브 구조물의 압력을 대기압 이하로 유지하는데에 사용될 진공 펌프의 용량을 설정하기 위한 파라메타 연구를 수행하였다. 최근 철도 기술 연구자들은 초고속 수송 시스템의 하나인 튜브 열차 시스템에 관심을 가지게 되었다. 초고속을 달성하기 위하여 튜브 내부를 저압으로 유지할 필요가 있는데, 저압에서는 공기 저항이 극단적으로 줄어들기 때문이다. 진공 펌프 시스템은 튜브 내부를 저압으로 만들고, 누설을 보충하는 역할을 한다. 일련의 연구결과, 다양한 파라메타에 대한 진공 펌프의 용량을 구하였다. 이 결과들은 공기 저항 저감 효과를 분석하는데에 적용될 것이다.

• 응용통계연구
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• 제17권2호
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• pp.253-267
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• 2004

임상시험중에는 소아암연구에서와 같이 환자 중의 상당수에서 사망 또는 재발이 오랜 기간 일어나지 않고 완치된 것으로 보이는 경우가 있다. 이 경우 연구자는 생존함수의 전반적인 비교보다는 치료율의 비교에 더 관심이 있을 것이다. 본고에서는 치료율의 비교를 위한 여러 모수적, 비모수적 방법들을 소개하고, 생존분포, 치료율, 중도절단을 등을 다양하게 설정한 모의실험을 통하여 각 방법들의 검정력과 유의수준을 비교하였다.

• 한국강구조학회 논문집
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• 제18권6호
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• pp.687-696
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• 2006

본 논문에서는 공간 뼈대구조의 탄-소성 후좌굴 강도를 파악하기 위한 효율적인 수치해석 기법을 개발하고, 매개변수해석을 통하여 보-기둥 및 뼈대구조물의 비탄성 후좌굴 거동을 분석하였다. 외력의 증가에 따라 점진적인 강도감소효과를 효율적으로 고려하는 개선된 소성힌지 해석법을 적용하여 문헌에서 제시된 다양한 잔류응력 분포 형태에 따른 뼈대구조물의 탄-소성 해석을 수행하였다. 요소의 소성화 진행정도를 나타내는 파라미터들을 도입하고 등가단면력 및 요소분할에 따른 매개변수해석을 수행하여 그 결과를 문헌에서 제시된 소성영역해석, 쉘요소를 이용한 정밀해석 그리고 실험결과와 비교하여 뼈대구조물 극한강도를 평가하였다.

• 대한가정학회지
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• 제48권5호
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• pp.25-48
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• 2010

The purpose of this study was to employ the Latent Growth Curve Model(LGM) to investigate the developmental trajectories of children's internalizing and externalizing problem behaviors and to identify predictors that might have an effect on change and the level of developmental trajectories. Furthermore, we classified the developmental trajectories of children's internalizing and externalizing problem behaviors, and also analyzed factors which caused differences in developmental trajectories by Semi-Parametric Group-based Modeling. This study used data from wave 1-4(2004~2008) of elementary school fourth grade panel of the Korea Youth Panel Survey(KYPS). The results showed that children's internalizing and externalizing problem behaviors changed significantly from the fourth grade of elementary school to the first grade of middle school. The predictors for developmental trajectories of children's internalizing problem behaviors were gender, self-control, parental conflict, deviant peers, and attachment to teachers. The predictors for the developmental trajectories of children's externalizing problem behaviors were gender, self-esteem, self-control, and deviant peers. The developmental trajectories of children's internalizing problem behaviors was classified into three groups. The developmental trajectories of children's externalizing problem behaviors was classified into four groups.