• Proceedings of the Korea Society for Simulation Conference
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• 2001.05a
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• pp.113-118
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• 2001

교통혼잡의 묘사를 보다 구체적으로 하기 위한 Mesoscopic시뮬레이션 모형으로서 INTEGRATION을 소개한다. 모형의 기본구조가 설명되고, 특히 응용사례로서 경부고속도로 축을 중심으로 한 주거지역의 급속한 팽창으로 야기된 고속도로상의 교통대안을 평가하려는데 초점을 맞추고 있다. 교통대안은 혼잡을 완화시키는데 타당하고 기술적으로도 실현가능한 대안이 제시된다. 이러한 대안들은 거시 및 미시 모의실험모형을 통해 면밀히 분석 평가되며 또한 대안을 도출하고 평가하는 과정의 제시로서 교통량조사에 근거한 OD 도출, Subarea 네트워크 분석 및 통합된 네트워크 모의실험과 같은 새로운 기법들이 아울러 제시된다. 대안의 대부분은 네트워크 개선에 관련한 것이다. 반포 IC 진출입로 공사(Al), 위빙 제거를 기초로 한 서초 IC TSM(A2), 서초-양재 구간의 고속 저속 분리(A3), 헌릉 IC(A4)의 신설, 판교 JC 개선(A5), 백현 IC(A6)신설. 가장 자본 집약적인 대안은 A4, A6순이다. A1, A5, A6은 구간은 짧으나, 자본 집약적이며 어느 정도의 공사 기간이 소요된다. 가장 비용이 적게 소요되는 대안은 A2, A3이다. A2는 시행이 용이하나, A3의 경우 공사기간 중 교통분산 대책이 필요하다. A1, A6은 속도증가와 통행시간 절감의 측면에서 가장 비용대비 효율적인 것으로 분석되었다. 시뮬레이션의 한계 및 개선방안이 함께 검토되었다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.7
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• pp.26-31
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• 2003

In this paper, supersonic jets impinging on axisymmetric cone were investigated to obtain fundamental design data for jet deflector case of example being VTOL/STOL or rocket launch. It was of interest to study flow phenomena such as shock interactions and separation induced by shear layer. Experiments were conducted to obtain schlieren flow visualization and measurement of surface pressure. Numerical results are compared with the experimental result. The dominant feature of the flow is the shock pattern induced by the interaction between the cone shock and the barrel shock. This pattern can take a wide variety of forms depending on the structure of the free jet and strongly influences the form of the surface pressure distributions.

• Journal of Biomedical Engineering Research
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• v.20 no.5
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• pp.601-608
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• 1999

동맥의 일부분의 팽창하는 동맥류는 높은 사망률을 야기하는 혈관계 질환이다. 동맥류의 발생 및 파열에는 동맥류 내부의 혈류의 유동에 의한 혈관벽 전단 응력 및 압력이 주용한 원인 중 하나로 의심되고 있다. 복부대동맥류 내부의 혈류 유동 특성을 밝히기 위해서 동맥류의 최대 확장부가 복부동맥의 1.5배, 2배인 유리 모델을 제작하였다. 정상류 상태에서 다양한 레이놀즈수에 대해서 속도 및 난동도를 입자영상속도계를 이용하여 측정하였다. 경계층 박리로 인한 재순환 부분이 끝나는 재부착점은 동맥류 최대 확장부 후부에서 발생하였으며, 이 위치는 레이놀즈수의 변화에 따라 바뀌었다. 축방향 속도의 난동은 최대 확장부 후부에서 크게 나타났으며, 이 위치에서 난동에 의한 부가적 응력이 크며 혈관벽 구조변화가 발생하리라 예측된다. 동맥류 내부의 압력분포는 수치해석에 의해 계산되었다. 동맥류 내부 압력은 크기가 증가함에 따라 커졌으며 압력은 동맥류 최대 확장부 후부에서 발생하는 재부착점에서 최대값을 나타내었다. 동맥류 최대확장부 후부는 압력이 최대값을 가지며, 전단력의 변화 및 난동이 큰 지역이므로 동맥류의 파열이 발생하기 쉬운 지역으로 예측된다.

• Journal of the Korean Geosynthetics Society
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• v.13 no.4
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• pp.153-159
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• 2014

During the winter and spring seasons in Korea, structures such as buried water supply pipelines, roads, railways are frequently damaged due to frost heaving and thawing. Until now, the method of substituting the frost susceptible soil with the gravel or rubbles those are non-frost susceptible materials have been employed in Korea to prevent frost heaving. A series of laboratory soil tests and indoor frozen soil engineering experiments, as well as laboratory frost heaving tests were conducted for seeking the means of utilizing recycled PET bottles as substitute material.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.11a
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• pp.1292-1295
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• 2012

인구 과밀화 및 급격한 도시 팽창은 지상공간에서 거주하는 인간 삶의 질을 위협하고 있다. 따라서 지상공간의 개발을 억제하여 환경을 보호하고 도시 공간 이용의 효율성을 최대화하기 위해 지하 공간을 개발하고자 하는 움직임이 활발하다. 자연환경으로부터 격리된 구조인 지하공간은 지상공간에 비해 실내 공기 질을 쾌적한 상태로 유지하기 어려운 밀폐된 환경이므로 오랜 시간동안 상주하는 거주자 및 한시적 이용자들의 건강에 영향을 미치는 온도, 습도, $CO_2$, 먼지 등의 환경을 제어하기 위한 기술 개발이 필요하다. 본 연구에서는 지하공간의 쾌적도 향상을 위해 온 습도 및 $CO_2$, 먼지센서를 이용한 통합 센서를 제작하여 현재 지하공간의 환경정보를 실시간 모니터링하고 실내공간의 쾌적 지표를 기반으로 환풍기, 송풍기 등의 디바이스를 제어하기 위한 USN 기반의 환경제어시스템을 구현한다. 제안한 시스템을 통해 지하공간의 환경을 개선할 뿐만 아니라 고가의 계측 장비로 인한 비용 절감 및 이동성과 확장성 등의 부가적인 효과를 기대한다.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.35 no.12
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• pp.157-164
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• 2019

Superabsorbent polymers(SAPs) are powdery material that absorb water several tens or hundreds of times its own mass. It has been reported that when SAPs are incorporated into a high strength cementitious material, the autogenous shrinkage of the material is reduced. Cross-linked sodium polyacrylate type SAPs are relatively safe for human body and low in production cost. In order to apply this type of SAPs to the admixture for total(plastic+autogenous+drying) shrinkage reduction of high strength mortar, the shrinkage behavior of mortar when an expansion agent(EA) and SAPs were mixed together was analyzed. As a result, it was found that the shrinkage was reduced when an EA 5% (mass % of cement) and SAPs 0.4% were mixed together than the mortar containing only an EA 10%. The shrinkage was further reduced when EA 10% and SAPs 0.4% were incorporated into mortar.

• Journal of the Korean Institute of Gas
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• v.25 no.1
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• pp.7-13
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• 2021

The re-liquefaction drum is a product that installed spray nozzles at the top to directly spray overcooled LNG into evaporative gas and installed demistors to facilitate gas separation, which was developed to increase the re-liquidity efficiency of small scale re-liquefaction facilities. In the hydrostatic test of the drum, no leakage occurred even at a pressure of 1.5 times the design pressure, but during the BOR(Boil Off Rate) test, the bolt loosening occurred due to contraction and expansion by temperature change. For the continued use of the product, insulation construction on flange connections was developed to enable detachment and attachment, and the comparison of heat load with existing insulation confirmed that it was very small compared to the inlet flow rate in the drum.

• Journal of the Society of Naval Architects of Korea
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• v.59 no.1
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• pp.29-38
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• 2022

In offshore installations, fires cause the structure to lose its rigidity and it leads to structural integrity and stability problems. The Passive Fire Protection (PFP) system slows the transfer rate of fire heat and helps prevent the collapse of structures and fatality. Especially, intumescent epoxy coating is widely used in the offshore industry, and not only is the material cost expensive, but it also takes a lot of time and cost for construction. Several studies have been conducted on the efficient application and optimal design of the PFP system. However, the mechanical properties and the strength of the PFP material have not been considered. In addition, researches on the correlation between the thickness of PFP and the structural behavior were insufficient. Therefore, this study aims to analyze the thermal and mechanical effects of the PFP on the structure when it is applied to the structural member. In particular, it is intended to resolve the change in strength characteristics of the structural members as the thickness of the PFP increases.

• Korean Journal of Materials Research
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• v.3 no.6
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• pp.624-631
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• 1993

The composites in the system aluminium titanate-mullite were synthesized by stepwise alkoxide hydrolysis of tetraethylorthosilicate, Si(OCLH5), and titaniumtetraethoxide, $Ti(OC_{2}H_{5})_4$ in $Al_{2}O_{3}$ ethanolic colloidal solution. All particles produced by sol-gel-process were amorphous, monodispesed and had a narrow particle size distribution. Sintered bodies at $1600 ^{\circ}C$ for 2h were subjected to prolonged durability tests-on the one hand annealing at the critical decomposition temperature of $1100 ^{\circ}C$ for lOOh and on the other cyclic thermal shock between 750 and $1400 ^{\circ}C$ for 100h. The best thermal durability was achieved by a composition containing 70 and 80 vol% aluminium titanate, which showed little change in microstructure and thermal expansion cycles during the tests. The microstructural degradation of samples studied using scanning electron microscopy, X-ray diffraction, and dilatometry, was presented here. The study was conducted in order to predict the service life of aluminium titanate-mullite ceramics formed by this processing route.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.7
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• pp.4093-4099
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• 2014

In this study, the thermal-structural behavior of the combustor assembly of 200 kW micro gas turbine system was performed. The typical combustor assembly consists of a Liner, Inner & Outer Case, Burner and Nozzle ring, etc. There are some gaps and friction elements between the components to compensate for the different thermal expansions of various components. Therefore, the developed finite element model includes nonlinear elements. The boundary support conditions of the combustor assembly significantly affect the stress distribution due to the high temperature gradient. This paper deals with parametric studies to quantitatively determine the effects of the variation of the support conditions on the stress distribution and deformation of various components of combustor assembly. These results may be useful for the design of the combustor assembly.