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마경훈,오한진 한국도로학회 2024 한국도로학회논문집 Vol.26 No.2
PURPOSES : Snow-removal performance is performed in this study to assess the feasibility of replacing calcium-chloride solution with sodium chloride solution at the minimum temperature of -5 ℃ during snowfall. METHODS : The atmospheric temperature distribution in Seoul was analyzed. The manufacturing, storage, and indoor melting performance of calcium-chloride and sodium-chloride solutions were evaluated, and on-site snow-removal performance was evaluated based on the solution type. RESULTS : According to the results of the melting performance test at -5°C, the melting capacity of the sodium chloride solution was expressed at a level exceeding 90% of that of the calcium chloride solution, indicating a similar melting performance between the two solutions. Additionally, based on the snow removal performance test using aqueous solutions, the snow removal performance of the sodium chloride solution was found to be approximately 96% compared to that of the calcium chloride solution, indicating minimal differences in snow removal performance due to changes in the type of solution. CONCLUSIONS : Similar snow-removal performance was achieved when the sodium chloride solution was used instead of calciumchloride aqueous solution at temperatures exceeding -5 ℃.
GPR 시스템 기반 교면포장의 콘크리트 바닥판 상태 평가방법에 대한 연구
마경훈,이진욱,오한진,이상염,김기덕 한국도로학회 2022 한국도로학회논문집 Vol.24 No.1
PURPOSES : In this study, a method for evaluating concrete bridge deck deterioration using three-dimensional (3D) ground penetrating radar (GPR) survey data and its in situ application are discussed. METHODS : Field surveys are conducted on two bridges in Yongsan-gu (Bridge A) and Seodaemun-gu (Bridge B) in Seoul using 3D GPR. The obtained survey data are used to calculate the dielectric constant map of each bridge using the extended common midpoint method. In addition, random points on both bridges are selected for the chloride content test in accordance with the KS F 2713 standard. The results from the dielectric constant map and chloride content test are compared. RESULTS : For Bridge A, it is discovered that the percentage of sections with a dielectric constant of 5.0 or less is 1.57%, whereas that above 5.0 is 98.43%; this indicates that the percentage of deteriorated sections for Bridge A is low. Meanwhile, for Bridge B, the dielectric constants calculated for the entire bridge exceed 5.0, which suggests no deterioration for Bridge B. Moreover, all the points selected for the chloride content test have less than 0.15% chloride content and have dielectric constants ranging from 5.0 to 7.0, which are favorable condition for the bridge deck. CONCLUSIONS : The analysis results of the dielectric constants of the concrete bridge deck obtained from the 3D GPR system are consistent with the actual chloride content results. Furthermore, additional verification of this method through field surveys on bridge sections with severe deterioration is highly recommended for future improvements.
마경훈(Kyung-Hoon Ma),이상호(Sang-Ho Lee) 한국정보과학회 1999 정보과학회 컴퓨팅의 실제 논문지 Vol.5 No.2
웹과 CORBA(Common Object Request Broker)의 통합은 사용자에게 많은 장점을 제공하며, 현재 이를 자바(Java) 언어로 구현한 JavaORB는 다수의 제품이 나와 있다. 본 논문에서는 Java ORB의 기능을 향상시키는 이름 에이젼트(naming agent)의 설계 및 구현에 관하여 기술한다. 이름 에이젼트는 두 가지 기능을 웹 사용자에게 제공한다. 첫째, 이름 에이젼트는 웹 사용자에게 기존의 CORBA 이름 서비스를 제공하며, 또한 모든 이름 서비스에 등록된 모든 객체 구현에 대한 통합된 이름 서비스 기능을 제공한다. 둘째, 이름 에이젼트는 자바로 구현된 CORBA 객체를 사용자 브라우저에서 직접 실행할 수 있도록 하는 기능을 제공한다. Integration of the Web and CORBA (Common Object Request Broker Architecture) provides a number of benefits to end users. Currently there are several JavaORBs in the market, which integrate CORBA and the Web with Java language. This paper addresses design and implementation of a naming agent which improves functions of the JavaORB. The naming agent provides two new benefits to Web users. First, the naming agent not only supports the CORBA naming service as it is, but a1so provides an integrated naming service, so that Web users are able to locate an object implementation by use of its name regardless of location of CORBA objects and naming service objects. Second, the naming agent allows users to access and run directly CORBA objects that are written in Java, at the Web browser.
환경하중과 B777 항공기 기어하중을 이용한 공항 콘크리트 포장의 최대인장응력 예측모형 개발
김동혁,마경훈,박해원,정진훈 한국도로학회 2018 한국도로학회논문집 Vol.20 No.5
PURPOSES : Previously, airport concrete pavement was designed using only aircraft gear loading without consideration of environmental loading. In this study, a multiple-regression model was developed to predict maximum tensile stress of airport concrete pavement based on finite element analysis using both environmental and B777 aircraft gear loadings. METHODS: A finite element model of airport concrete pavement and B777 aircraft main gears were fabricated to perform finite element analysis. The geometric shape of the pavement, material properties of the layers, and the loading conditions were used as input parameters for the finite element model. The sensitivity of maximum tensile stress of a concrete slab according to the variation in each input parameter was investigated by setting the ranges of the input parameters and performing finite element analysis. Based on the sensitivity analysis results, influential factors affecting the maximum tensile stress were found to be used as independent variables of the multi regression model. The maximum tensile stresses predicted by both the multiple regression model and finite element model were compared to verify the validity of the model developed in this study. RESULTS: As a result of the finite element analysis, it was determined that the maximum tensile stress developed at the bottom of the slab edge where gear loading was applied in the case that environmental loading was small. In contrast, the maximum tensile stress developed at the top of the slab center situated between the main gears in the case that the environmental loading got larger. As a result of the sensitivity analysis and multiple regression analysis, a maximum tensile stress prediction model was developed. The independent variables used included the joint spacing, slab thickness, the equivalent linear temperature difference between the top and bottom of the slab, the maximum take-off weight of a B777 aircraft, and the composite modulus of the subgrade reaction. The model was validated by comparing the predicted maximum tensile stress to the result of the finite element analysis. CONCLUSIONS : The research shown in this paper can be utilized as a precedent study for airport concrete pavement design using environmental and aircraft gear loadings simultaneously.