• Journal of Korean Society of Steel Construction
• /
• v.16 no.6 s.73
• /
• pp.725-736
• /
• 2004

A new type of girder, called steel-confined prestressed concrete girder (SCP girder), has been developed, which maximizes the structural advantages of concrete, steel, and PS tendon, and improves on the shortcomings of steel plate girder, PSC I-girder, and preflex girder bridge for use in the construction of middle- or long-span bridges. To verify the propriety of design, structural safety, and applicability of this girder, a static load test was carried out (Kim et al.., 2002). Since the main damage typically sustained by steel bridges results from the fatigue caused by the repetition of traffic loads, fatigue safety must therefore be guaranteed in applying the SCP girder in the construction of real bridges. In this study, a fatigue test was carried out to investigate fatigue behavior and provide basic data for fatigue design. Based on the fatigue test, the fatigue safety of the girder was estimated. For the fatigue test, 10-m specimens were designed for a standard-design truckload (DB-24). A static load test was also performed before the fatigue test to analyze the structural behavior of the specimens. After the fatigue test, outer steel plates were removed to observe the condition of the concrete in the girder.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.15 no.5
• /
• pp.92-100
• /
• 2011

This paper describes a numerical modeling for deflection calculation using the natural frequency response that is measured acceleration response for concrete bridges. In the formulation of the dynamic deflection, the change amounts and the transformed responses about six kinds of free vibration responses are defined totally. The predicted response can be obtained from the measured acceleration data without requiring the knowledge of the initial velocity and displacement information. The relationship between the predicted response and the actual deflection is derived using the mathematical modeling that is induced by the process of a acceleration test data. In this study, in order to apply the proposed response predicted model to the integration scheme of the natural frequency domain, the Fourier Fast Transform of the deflection response is separated into the frequency component of the measured data. The feasibility for field application of the proposed calculation method is tested by the mode superposition method using the PSC-I bridges superstructures under several cases of moving load and results are compared with the actually measured deflections using transducers. It has been observed that the proposed method can asses the deflection responses successfully when the measured acceleration signals include the vehicle loading state and the free vibration behavior.

• Proceedings of the Korean Institute Of Construction Engineering and Management
• /
• 2008.11a
• /
• pp.197-201
• /
• 2008

Conceptual cost estimates for domestic highway projects have generally been conducted using governmental unit-price references. Inaccuracies in governmental unit-price data has repeatedly addressed in the Korean construction industry which often lead to poor decision making and cost management practices. Thus, needs for developing a better way of conceptual cost estimating has been widely recognized. This research is considered as the first step in developing such model using real-world cost data based on actual construction activities. The data analyzed in this paper includes 41 P.S.C (Prestressed Concrete) Box bridges which broke into 4 categories based on construction methods such as I.L.M(Incremental Launching Method), M.S.S(Movable Scaffolding System), F.S.M(Full Staging Method), and F.C.M(Free Cantilever Method). Actual design documents; including actual cost estimating documents, drawings and specifications were carefully reviewed to effectively break down cost structures for PSC girder bridges. Among more than 40 cost categories for each P.S.C girder bridge type, 7 of them were identified which accounted for more than 95% of total construction cost (ILM: 99.47%, MSS: 99.22%, FSM: 98.18%, and FCM: 98.12%). In order to validate the clustering of cost categories, the variation of each cost category has been investigated which resulted in between -1.16 % and 0.59%.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
• /
• v.2 no.1
• /
• pp.160-175
• /
• 1991

The purpose of this study is to investigate the parental marital relationships and the parent-child relationships of child psychiatric parents and its control group. This study was carried out two questionnaire instruments ; The marital satisfaction inventory(MSI) and the dyadic adjustment scale(DAS). The subjects are parents of the child psychiatric patients. A matched control group and parents of child psychiatric parents in Seoul area which were collected from July 1987 to September 1987, and classified into five subgroups : 1 Psychiatric disorder 2) Neurotic disorder 3) Tic disorder 4) Autistic disorder 5) Mental retardation. The results are as following ; 1) M.S.I scale scores of parents of patients group are lower than that of control group. 2) D.A.S scale score of parents of patients group is significantly lower than that of the control group(P<0.01). 3) The global distress scale(GDS) of the M.S.I. was most positively correlated with affective communication(AFC) and problem-sloving communication(PSC). 4) Female shoed more modern concept of role identification than male but tend to have heavier role assignment especially in child rearing practices which could be characterized by maternal domination. 5) Affective communication and sexual relationship between married couple and child rearing practices are influenced by their own family history of distress. 6) The marital global distress scale(GDS) score was highest in the parents of psychosis, the next in the parents of neurosis, autism, mental retardation, and tic disorder in descending order of severity. 7) The dyadic maladjustment score was highest in the parents of psychosis, the next in the parents of neurosis, tic, autism and mental retardation in descending order of severity. 8) Conflict in child rearing and parenting problems were particularly prominent in parents of the tic patients, and their marital relationship was not significantly disturbed. The above finding suggested that couple adjustment and marital dissatisfaction were closely related with child rearing problems and the children's disorder. So marital dissatisfaction and marital maladjustment seem to play a significant role in the genesis of psychosis and neurosis not much in autism and mental retardation.