자세제어 기술을 이용한 안전 유모차

유주호(Juho Yoo),이진영(Jinyoung Lee),로뢰(Lu Lei),이용희(Yonghee Lee) 한국HCI학회 2013 한국HCI학회 학술대회 Vol.2013 No.1

최종목표는 유모차의 아이가 앉는 부분을 모터를 이용하여서 어떤 경사면에서도 항상 지표면과 수평을 유지 할 수 있도록 제어하여 유모차의 안정감을 높여주는 것이다. 본 논문에서는 자세제어기술을 유모차에 최대한 적절히 접목시키기 위한 과정으로써 하드웨어 설계, 부품 선정 과정, 모터제어과정 등을 다루도록 한다. The quality of motion control system has been greatly improved motion control system has been used in many areas due to the development of electronic and motors, auto control technology and micro controller unit(MCU). Based on the design of a show system, a motion control system of baby carriage controlled by ATmega128 MCU has been put forward in this paper. The motion control system is designed in the designing model of MCU plus motion controller plus motor, in which the motion control command to the motor, including sending pulse signals to control the motor. In this paper, the control method and realization of the baby carriage have been analyzed and discussed firstly. Then the designing and application of the hardware and software are performed in this paper. In discussing the hardware design, the hardware communication between the MCU is discussed at first, then the connection of MCU and motion controller and at last the connection of MCU and sensors. In the software part, the flow chart of the main program will be given out. And then according to the chart, the software design of communication between MCU is discussed in the first place, followed are the MCU control of motion controllers. In the end, the design of how to get the position of the baby carriage will be discussed. The design of software and hardware put forward in this paper has been successfully developed to practical application of the system. It is proved that the system meets the design requirements and has achieved good results.

폐비닐 골재가 혼합된 시멘트 콘크리트의 열 특성

염우성,안기홍,유주호,정진훈 한국도로학회 2014 한국도로학회논문집 Vol.16 No.6

PURPOSES : In this study, wasted vinyl aggregate, which possesses better thermal properties than natural aggregate, was used in cement concrete mixture to develop more economical concrete with thermal insulation and freeze prevention effects. METHODS : Slump and air content of the fresh concrete, which substituted its 0%, 5%, and 10% of coarse aggregate with wasted vinyl aggregate, were measured. Compressive strength, Poisson’s ratio, elastic modulus, and splitting tensile strength of hardened concrete were measured by laboratory tests. Thermal properties of concrete such as coefficient of thermal expansion, thermal conductivity, and specific heat were also measured according to replacement ratio of wasted vinyl aggregate. Finally, the thermal insulation and freeze prevention effectiveness of the concrete mixed with wasted vinyl aggregate was confirmed through finite element analysis of road pavement crossing above concrete box culvert made from wasted vinyl aggregate. RESULTS: Even though the physical properties of wasted-vinyl-aggregate concrete such as compressive strength, Poisson°Øs ratio, elastic modulus, and splitting tensile strength were inferior to those of ordinary concrete, they met requirements for structural concrete. The thermal properties of concrete were improved by wasted vinyl aggregate because it decreased thermal conductivity and increased specific heat of the concrete. According to the result of finite element analysis, temperature variation in pavement subgrade was mitigated by box culvert made from wasted-vinyl-aggregate concrete. CONCLUSIONS: Through the laboratory test and finite element analysis of this study, it was concluded that the concrete structures made from wasted vinyl aggregate showed thermal insulation and freeze prevention effects.

FWD 방향을 고려한 콘크리트 포장 하부 상태 평가

이재훈,이재훈,손덕수,유주호,정진훈 한국도로학회 2014 한국도로학회논문집 Vol.16 No.6

PURPOSES: The purpose of this paper is showing that the state of pavement sublayers can be evaluated differently according to direction of FWD. METHODS: The concrete pavement slabs above subgrade without anything, subgrade with cavity, and box culvert were modeled by finite element method(FEM). The modeled pavements were analyzed by changing the direction of falling weight deflectometer(FWD). The deflection results obtained from FEM were used to calculate radius of relative stiffness and composite modulus of subgrade reaction using AREA method. Then, the analyzed results were compared to the results of the test performed at the Korea Expressway Corporation(KEC) test road. RESULTS : The composite modulus of subgrade reaction increased with subgrade elastic modulus, while radius of relative stiffness decreased. The pavement sections of pure earth showed the consistent results regardless of FWD direction. In case there was cavity, the radius of relative stiffness was larger and composite modulus of subgrade reaction was smaller when FWD was leaving the cavity than when approaching the cavity. This pattern became clear when the cavity got larger. In case of the section with box culvert, the pattern was opposite to the case of cavity. When the soil cover depth increased, the effect of box culvert got smaller. When the load was applied far from the cavity and box culvert, the effect was also declined. The test performed at the KEC test road showed identical results to those of finite element analysis. CONCLUSIONS : The direction of FWD should be considered in evaluation of the state of pavement sublayers because it can be evaluated differently even under identical condition.

PCI 분석을 통한 공항 콘크리트포장 공용수명 예측

김승재,유주호,김태훈,이제일,이재훈,정진훈 한국도로학회 2014 한국도로학회 학술발표회 논문집 Vol.2014 No.3

환경하중과 DT 기어 하중에 기인한 콘크리트 포장 응력의 회귀모형 개발

이기상,유주호,이재훈,정진훈 한국도로학회 2014 한국도로학회 학술발표회 논문집 Vol.2014 No.9

현재 공항에서 주로 사용되는 콘크리트 포장은 미국 연방항공청(FAA) 및 국제 민간항공기구(ICAO) 등 에서 제시한 경험적 설계를 하고 있으나 이러한 경험적 설계는 공학적 개념이 부족하여 정확하지 않으며 더욱이 최근 사용되는 역학적-경험적 설계법은 공학적 검증 없이 해외의 설계법을 사용하여 국내 실정에 맞는 설계법이 필요하다. 또한 기존의 설계방법은 설계인자 중 환경하중을 고려하지 못하여 정확한 설계 에 어려움이 있다. 따라서 본 논문에서는 환경하중을 고려하기 위해 공항에 따른 지역별 기후를 고려하여 지역별 연평균 일교차와 연평균 상대습도를 반영한 등가온도차이를 적용하였으며 교통하중의 경우 설계 항공기 중 대형항공기에 해당하는 Duals in Tandem(DT) 기어형상을 적용하였다. DT기어가 재하 될 때 슬래브에서 발생하는 최대인장응력의 위치를 확인하기 위해 유한요소해석 프로그 램인 FEAFAA 2.0을 사용하여 해석을 실시하였으며, 그 결과 교통하중만 작용할 때와 환경하중을 고려한 교통하중이 작용할 때의 최대인장응력 발생 위치는 서로 상이하였고 이를 고려하여 회귀식 산정을 위한 유한요소해석을 실시하였다.이어 합리적인 응력회귀식을 산정하기 위해 포장에 영향을 미칠 것으로 예상 되는 인자를 선정하였으며, 이를 민감도 분석한 결과 슬래브 두께(), 기어하중( ), 줄눈간격(), 슬래브 하부 지지력계수( )가 기준응력에서 5% 이상의 슬래브 응력 거동에 영향을 주는 주요 인자로 선정되었 다. 또한 역학적 설계에 따라 국내 공항의 환경 및 설계항공기의 기어 특성을 고려하여 앞서 민감도 분석 을 통해 결정된 인자들을 바탕으로 DT기어의 교통하중만 작용할 때와 교통하중과 환경하중을 모두 고려 했을 때 의 경우에 대해서 해석을 실시하였다. 이러한 해석결과를 바탕으로 사회과학 통계프로그램(SPSS)을 이용한 다중회귀분석을 실시하여 회귀식 을 산출하였다. 교통하중의 경우 네 개의 독립변수에 대한 회귀식이며, 환경하중을 고려한 교통하중의 회 귀식은 환경하중 회귀식(김연태, 2014)을 통해 얻은 결과를 활용하여 복합하중에 대한 회귀식을 얻었다. 교통하중에 대한 회귀식은 상관계수가 0.994로서 종속변수에 대한 독립변수들의 상관도가 매우 높음을 확인할 수 있었으며, 유의확률 및 다중공선성이 0.000과 10이하의 값으로서 각 인자들 간에 영향을 주는 정도가 낮은 것으로 판단되었다. 다음 두 식은 DT 기어에 대한 교통하중과 환경하중을 고려한 교통하중 의 회귀식이며 각 인자들의 계수를 비교함으로서 응력거동에서 영향을 주는 정도를 확인할 수 있다.

Application of Environmental Loading in Mechanistic Design of Airport Concrete Pavements

서진석,박해원,유주호,최민규,최기효,정진훈 한국도로학회 2019 한국도로학회논문집 Vol.21 No.6

PURPOSES : Almost every design method for airport concrete pavements considers only traffic loading and not environmental loading. This study proposes a mechanistic design method for airport concrete pavements, that considers both environmental and traffic loading simultaneously. METHODS: First, the environmental loading of concrete pavements in Korean airports was quantified. FEAFAA, a finite element analysis program for airport pavements, was used to calculate the maximum tensile stress (MTS) of the slab, caused by both environmental and traffic loadings. The factors that influence the MTS were identified via sensitivity analysis, and an MTS prediction model was developed using the statistical analysis program SPSS. The ratio of MTS to the tensile strength of slab was calculated using the prediction model. The fatigue model under the AC 150/5320-6E and AC 150/5320-6F standards of the FAA was corrected to make it suitable for the predicted stress-strength ratio. RESULTS : The MTS prediction model and corrected fatigue model were used to redesign the slab thickness and joint spacing of airport concrete pavements originally designed using the AC 150/5320-6D standard, which empirically considers traffic loading only. As a result, different slab thicknesses and joint spacings were redesigned with consideration for environmental loading, specifically the weather conditions of airports. . CONCLUSIONS: The slab thickness and joint spacing can be mechanistically designed at the same time, whereas previously, only the slab thickness was designed, and the joint spacing was determined empirically.

콘크리트 포장 슬래브와 보조기층 간 마찰특성 모형화

임진선,손석철,유주호,정진훈 한국도로학회 2010 한국도로학회논문집 Vol.12 No.4

Volume of concrete slab changes by temperature and moisture effects. At that time, tensile stress develops because the slab volume change is restrained by friction resistance between the slab and subbase, and then crack occurs occasionally. Accordingly, researchers have made efforts to figure out the friction characteristics between the slab and subbase by performing push-off tests. Lately, researches to analyze concrete pavement behavior by the friction characteristics have been performed by finite element method. In this study, The friction characteristics between the slab and subbase were investigated based on the friction test results for lean concrete, aggregate, and asphalt subase widely used in Korean concrete pavements. The energy method bilinearizing relation between nonlinear friction resistance and displacement were suggested. The friction test was modeled by 3-D finite element program, ABAQUS, and the model was verified by comparing the analyzed results to the test results. The bilinear model developed by the energy method was validated by comparing analysis results obtained by using the nonlinear and bilinear friction resistancedisplacement relation as input data. A typical Korean concrete pavement was modeled by ABAQUS and EverFE and analyzed results were compared to evaluate applicability of the bilinear model. 콘크리트 슬래브는 온도 및 수분의 영향을 받아 체적이 변화된다. 이때 슬래브와 보조기층 간의 마찰저항이 슬래브 체적변화를 구속하여 인장응력이 발생되고 경우에 따라 균열이 유발되기도 한다. 따라서 연구자들은 Push-off 실험을 실시하여 슬래브와 보조기층간의 마찰특성을 파악하려고 노력해 왔다. 최근에는 마찰특성에 의한 콘크리트 포장의 거동을 유한요소법으로 해석하려는 연구가 수행되었다. 본 연구에서는 국내 콘크리트 포장에 주로 사용되는 린콘크리트, 쇄석, 아스팔트 보조기층에 대하여 실시된 마찰실험 결과를 바탕으로 슬래브와 보조기층 간 마찰특성을 조사하였다. 비선형의 마찰저항과 변위의 관계를 이중선형화하는 에너지 방법이 제시되었다. 마찰실험을 3차원 유한요소 프로그램 ABAQUS로 모형화하였으며 해석결과를 실험결과와 비교하여 모형을 검증하였다. 비선형과 이중선형 마찰저항-변위 관계를 각각 입력값으로 사용하여 얻은 해석결과를 비교하여 에너지 방법으로 개발된 이중선형 모형의 타당성을 검증하였다. 일반적인 국내 콘크리트 포장을 ABAQUS와 EverFE로 모형화하고 해석결과를 비교하여 이중선형 모형의적용성을 평가하였다.

폐비닐 골재가 혼합된 시멘트 콘크리트의 열 특성

염우성,안기홍,유주호,정진훈 한국도로학회 2014 한국도로학회논문집 Vol.16 No.6

PURPOSES : In this study, wasted vinyl aggregate, which possesses better thermal properties than natural aggregate, was used in cementconcrete mixture to develop more economical concrete with thermal insulation and freeze prevention effects. METHODS : Slump and air content of the fresh concrete, which substituted its 0%, 5%, and 10% of coarse aggregate with wasted vinylaggregate, were measured. Compressive strength, Poisson’s ratio, elastic modulus, and splitting tensile strength of hardened concrete weremeasured by laboratory tests. Thermal properties of concrete such as coefficient of thermal expansion, thermal conductivity, and specific heatwere also measured according to replacement ratio of wasted vinyl aggregate. Finally, the thermal insulation and freeze preventioneffectiveness of the concrete mixed with wasted vinyl aggregate was confirmed through finite element analysis of road pavement crossingabove concrete box culvert made from wasted vinyl aggregate. RESULTS: Even though the physical properties of wasted-vinyl-aggregate concrete such as compressive strength, Poisson°Øs ratio, elasticmodulus, and splitting tensile strength were inferior to those of ordinary concrete, they met requirements for structural concrete. The thermalproperties of concrete were improved by wasted vinyl aggregate because it decreased thermal conductivity and increased specific heat of theconcrete. According to the result of finite element analysis, temperature variation in pavement subgrade was mitigated by box culvert madefrom wasted-vinyl-aggregate concrete. CONCLUSIONS: Through the laboratory test and finite element analysis of this study, it was concluded that the concrete structures madefrom wasted vinyl aggregate showed thermal insulation and freeze prevention effects.

Duals in Tandem 기어에 의한 공항콘크리트 포장 응력의 해석

정진훈,조윤수,이재훈,유주호 한국방재학회 2014 한국방재학회 학술발표대회논문집 Vol.2014 No.-

국내 공항 콘크리트 포장은 FAA 150/5320-6D에서 제시하는 설계법에 따라 설계대상항공기로 등가 환산된 교통량을 설계에 반영해 왔으나, 2006년에 개정된 FAA 150/5320-6E에서는 운항이 예상되는 모든 항공기의 연평균 이륙횟수를 설계에 반영하고 있다. 개정된 설계 기준에 따라 다양한 종류의 기어형상을 반영하는 것이 실제 교통량을 반영할 수 있으므로 더 합리적인 설계 방법이라 할 수 있다.<br> 본 연구에서는 Duals in Tandem(2D) 기어형상의 교통하중을 환산하기 위한 응력회귀식을 개발하였으며, 선행연구(김연태, 2013)인 Double Duals in Tandem(2D/2D2) 기어의 응력 회귀 모형 개발 절차에 따라 연구를 수행하였다. 또한 환경하중에 의한 응력 영향을 반영하기 위해 기존에 개발된 ‘지역별 슬래브 두께에 따른 등가선형 온도차이(홍동성, 2012)’를 사용하여 국내 기후특성을 반영하였다. 우선, 응력 회귀식 모형을 산출하기 위해 공항포장 설계에 필요한 각각의 설계인자들의 민감도 분석을 실시하였고, 영향력이 큰 주요 인자들의 설계 적용 범위를 정의 한 후, 선별된 설계 변수들을 유한요소 해석 프로그램(FEAFAA)에 적용하여 다양한 경우에서 유한요소해석(FEM)을 실시하였다. 또한, 해석결과인 최대인장응력을 종속변수로 적용하고, 해석에 적용한 설계인자들을 독립변수로 적용하여 다중회귀분석(SPSS)을 실시한 결과, 교통 및 환경하중에 의해 발생되는 최대인장응력 회귀식을 산출할 수 있었다. 개발된 회귀식은 각각 교통하중에 의한 응력회귀식, 환경하중과 교통하중을 동시에 고려한 응력회귀식이며, 입력변수로는 줄눈간격, 슬래브두께, 복합지지력계수, 등가선형온도차이, 교통하중이 있다. 또한, 회귀식 검증을 위해, 각각의 회귀식 변수를 변화시키며 유한요소해석 결과와 비교 분석을 실시하였다.

FWD 방향을 고려한 콘크리트 포장 하부 상태 평가

이재훈,이재훈,손덕수,유주호,정진훈 한국도로학회 2014 한국도로학회논문집 Vol.16 No.6

PURPOSES: The purpose of this paper is showing that the state of pavement sublayers can be evaluated differently according to direction ofFWD. METHODS: The concrete pavement slabs above subgrade without anything, subgrade with cavity, and box culvert were modeled by finiteelement method(FEM). The modeled pavements were analyzed by changing the direction of falling weight deflectometer(FWD). Thedeflection results obtained from FEM were used to calculate radius of relative stiffness and composite modulus of subgrade reaction usingAREA method. Then, the analyzed results were compared to the results of the test performed at the Korea Expressway Corporation(KEC) testroad. RESULTS : The composite modulus of subgrade reaction increased with subgrade elastic modulus, while radius of relative stiffnessdecreased. The pavement sections of pure earth showed the consistent results regardless of FWD direction. In case there was cavity, the radiusof relative stiffness was larger and composite modulus of subgrade reaction was smaller when FWD was leaving the cavity than whenapproaching the cavity. This pattern became clear when the cavity got larger. In case of the section with box culvert, the pattern was opposite tothe case of cavity. When the soil cover depth increased, the effect of box culvert got smaller. When the load was applied far from the cavity andbox culvert, the effect was also declined. The test performed at the KEC test road showed identical results to those of finite element analysis. CONCLUSIONS : The direction of FWD should be considered in evaluation of the state of pavement sublayers because it can be evaluateddifferently even under identical condition.