• 한국산업융합학회 논문집
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• 제25권5호
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• pp.881-888
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• 2022

Servo presses are used in variety of ways in industry throughout the production and assembly lines of machine parts. The bottom of the servo press is fixed to a bed or a tabletop, and the press cylinder continuously operates under vertical upward loads. In this research, a static structural analysis was performed by simplifying 3D model of the servo press, and the maximum deformation was applied to the clamp and bolt. The maximum value of Von Mises stress was reported in this paper. The result was used to calculate the safety factor, and it was confirmed that the design was conservative.

• Earthquakes and Structures
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• 제8권5호
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• pp.995-1016
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• 2015

The reliability or the safety index is a measure of how far a structure is from the state of collapse. Also it defined as the probability that a structure will not fail in its lifetime. Having any increase in the reliability index is typically interpreted as increasing in the safety of structures. On the other hand most of researchers acknowledged that one of the most effective means of increasing both the reliability and the safety of structures is to increase the structural redundancy. They also acknowledged that increasing the number of vertical seismic framing will make structural system more reliable and safer against stochastic events such as earthquakes. In this paper the reliability index and the behavior factor of a numbers of three dimensional RC moment resisting frames with the same story area, equal lateral resistant as well as different redundancy has been evaluated numerically using both deterministic and probabilistic approaches. Study on the reliability index and the behavior factor in the case study models of this research illustrated that the changes of these two factors do not have always the same manner due to the increasing of the structural redundancy. In some cases, structures with larger reliability index have smaller behavior factor. Also assuming the same ultimate lateral resistance of structures which causes an increase to a certain level of redundancy can enhance behavior factor of structures. However any further increase in the redundancy of that certain level might decrease the behavior factor. Furthermore, the results of this study illustrate that concerning any increase in the structural redundancy will make the reliability index of structure to be larger.

• 한국안전학회지
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• 제28권3호
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• pp.1-5
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• 2013

In order to evaluate fatigue endurance for an MTB(mountain bike) frame, FEM(finite element method) analysis was performed. For evaluating the fatigue endurance of the MTB frame, the S-N data for Al-6061 fillet weldment were compared with the stress analysis results through FEM analysis of the frame. Three loading condition, pedalling, horizontal and vertical loading conditions were considered for fatigue endurance evaluation. Horizontal loading(+1200 N) condition was found to be the most severe to the frame. The maximum von Mises stress of the frame under horizontal loading(+1200 N) condition was determined 294 MPa through FEM analysis of the frame. Conclusively, on the basis of fatigue strength of 200 MPa at the number of cycles of 50,000, the MTB frame has an improper safety factor of approximately 0.25, suggesting that this frame needs reinforcement.

• 한국안전학회지
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• 제28권6호
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• pp.84-89
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• 2013

The main causes of traffic accidents can be classified by 3 factors - human error, vehicle deficiency and road environmental problem and most accidents occurs not only 1 factor but combination of 2 or 3-factors. Among these factors, road environmental factor is the most important factor due to influence the behavior of cars and road users and road environmental factor affects 30% of total accidents approximately. The 5 years traffic accidents data analyzed to verify the accidents severity on Korea National Highways. In order to analyze the severity, Ordered Probit Model was used. As a independent variables of this model the number of lane, neighbor road environments, sight distance, vertical grade, lane width, shoulder width and traffic volume were used and as a dependent variables the minor injuries, serious injuries and fatalities were used. Research results shows that sight distance and lane width are identified as significant factors for the traffic accident severity and lesser sight distance and lane width shows greater traffic accident severity.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2001년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall 2001
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• pp.139-146
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• 2001

The seismic safety analysis were performed for the center-core rockfill dam(CCRD) The static and pseudo-static FEM analysis using seismic coefficient Method, and dynamic FEM analysis using Hachinohe earthquake wave(0.12g) were used for the seismic safety of CCRD. The results of seismic analysis were that the factor of safety of down slope was 1.5, horizontal displacement is about 14.3cm, and vertical displacement is 3.3cm at dam creast. The model dam did not show any seismic stability problems for 0.12g. And much more research is still necessary in seismic safety of CCRD.

• 한국안전학회지
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• 제38권3호
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• pp.61-68
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• 2023

This study performed a structural performance evaluation of a system scaffolding for elevator installation work developed in previous studies. The structural performance was evaluated via a structural test conducted to apply the working load specified in the design standard. The deflection of the horizontal member and the stress of each member constituting the system scaffolding were measured. Consequently, the structural safety evaluation including structural behavior and required performance was performed using the deflection and stresses measured from the structural test. The structural test and safety evaluation results based on the heavy working load corresponding to the design load indicated that the deflection, which is the performance criterion of the horizontal member, did not exceed the allowable value. Further, each member's stress, which is a safety evaluation indicator, did not exceed the allowable strength for both horizontal and vertical members with bending behavior and fordable bracing with tensile behavior, while also satisfying the required safety factor. In addition, the results confirmed the safety against deformation, partial damage, and destruction owing to excessive and maximum load. Therefore, the system scaffolding developed in this study satisfies both the structural performance and safety required by the design standards; thus, it can be applied to elevator installation work sites.

• 한국도로학회논문집
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• 제16권5호
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• pp.173-182
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• 2014

PURPOSES : The purpose of the study is to a) explore the operating speed of trucks on rural highways affected by road geometry, and thereby b) develop a predictive model for the operating speed of trucks on rural highways. METHODS : Considering that most of the existing studies have focused on cars, the current study aimed to predict the operating speed of trucks by conducting linear regression analysis on the speed data of trucks operating on the linear-curved-linear portions of the road as a single set. RESULTS : The operating speed in the plane curve portion increased with the length of the curve, and decreased with a lower vertical grade and a smaller curve radius. In the straight plane portion, the operating speed increased with a larger curve radius(upstream), and decreased with an increase in the change of the vertical grade, depending on the length of the vertical curve. CONCLUSIONS : This study developed estimation models of truck for operational speed and evaluated the degree of safety for horizontal and vertical alignments simultaneous. In order to represent whole area of the rural highway, the models should be ew-analyzed with vast data related with road alignment factor in the near future.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 춘계 학술발표회
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• pp.579-584
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• 2009

Arrangement of the facilities for improving harbor functions depends on sea and land conditions such as the ship's arrival and departure conditions, waves and tide. And the plan and the size of the facilities depend much on harbor and marine environment condition such as cargo quantity, ship size, ship traffic and seawater circulation. Among these, waves have so much effect on a breakwater design that it is the most important to understand their characteristics and to apply them to breakwater design. Therefore, to analyze the effect of waves characteristics over a rubble mound breakwater, we have calculated wave pressure by using numerical analysis at each tide level and have analyzed the effect of wave pressure on structure stability by conducting the stability analysis with the wave pressure. As a result, it is found that during low and mean tide level time the biggest wave pressure is estimated near calm water level. But during high tide time, the biggest wave pressure is estimated in front of capping. And the stability analysis indicates also that a structure is most unstable when low tide time wave pressure is acting on. After reviewing the stability of a structure by applying vertical and horizon wave forces, it is concluded that safety factor is lower than ordinary time(max. about 15%), is also reviewed when designing a rubble mound breakwater.

• 산업기술연구
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• 제3권
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• pp.103-116
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• 1983

Recent developments in multi-storey buildings for residential purpose have led to the extensive use of shear walls for the basic structural system. When the coupled shear wall system is used, joined together with cast-in-place concrete or mortar (or grout), the function of the continuous joints is a crucial factor in determining the safety of L.P. Precast concrete shear wall structures, because the function of the continuous joints(Vertical wall to wall joints) is to transfer froces from one element(shear wall panel) to another, and if sufficient strength and ductility is not developed in the continuous joints, the available strength in the adjoining elements may not be fully utilized. In this paper, the influence of the stiffness of vertical joints(wet vertical keyed shear joints) on the behaviour of precast shear walls is theoretically investigated. To define how the stiffness of the vertical joints affect the load carrying capacity of L.P.Precast concrete shear wall structure, the L.P.Precast concrete shear wall structure is analyzed, with the stiffness of the vertical joints varying from $K=0.07kg/mm^3$(50MN/m/m) to $K=1.43kg/mm^3$(1000MN/m/m), by using the continuous connection method. The results of the analysis shows that at the low values of the vertical stiffness, i.e. from $K=0.07kg/mm^3$(50MN/m/m) to $K=0.57kg/mm^3$(400MN/m/m), the resisting bending moment and shearing force of precast shear walls, the resisting shearing force of vertical joints and connecting beams are significantly affected. The detailed results of analysis are represented in the following figures and Tables.

• 한국항해학회지
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• 제15권1호
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• pp.49-65
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• 1991

It is of great importance for any vessel under way, especially in rough sea, to be maneuvered safely with proper seakeeping performance. In this paper, the author aims to develope a navigational safety evaluation system in rough sea by analyzing ship's with the theory of wave spectrum using random process analysis and the theory of evaluating the seakeeping performance. The scope and the method of this study are as follows ; (1) Modelized typhoon mathematically to represent the sea condition in rough sea. (2) Estimated sea conditions by getting wave spectrum, supposing that the wave by typhoon is fully developed short crest irregular wave. (3) Defined evaluation factor of vessel's seakeeping performance and obtained response amplitude operators thereby. (4) Obtained the response spectrum of factors on seakeeping performance. (5) Defined and obtained evaluation index, dangerousness, relative and maximum dangerousness of factors on seakeeping performance. (6) Analyzed the calculated dangerousness of evaluation index and picked the vertical acceleration out of 7 factors as the presentative factor on seakeeping performance. (7) Carrid out the judgement of danger by obtaining dangerousness value according to steaming hour, course alteration and speed change. By synthesizing the above items, the authors suggests a computer model of navigational safety evaluation system and examined the validity of the model by computer simulation.