• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.12
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• pp.6967-6972
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• 2014

Assembly using a bolt and nut, and rivet or pin have been used widely for forming mechanical joints. The indent method is an easier process than other manufacturing techniques and the toughness of the material is excellent. On the other hand, there are many cases in which the cracks occur on the manufacturing process as the indent method. Therefore, two kinds of models, in which a pin goes into and out PCB plate in this study were developed using the CATIA program and finite element methods were performed using the ANSYS program. When a pin was passed through a PCB plate in cases 1 and 2, the maximum loads applied to the PCB plate were 79.708N and 90.277N, respectively. When the PCB plate came out of the pin in cases 1 and 2, the maximum loads were 63.783N and 33.75N, respectively. The damage prevention and durability can be improved by applying the study results to the design of real indentation.

• Magazine of the Korean Society of Agricultural Engineers
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• v.27 no.4
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• pp.42-52
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• 1985

This study was attempted to derivate empirical formulas for the runoff: ratio during ilood. season at three watersheds of Dan Yang, Chung Ju, and Yeo Ju are located at upper, middle, and lower portion of Nam Han river basin, respectively. Obtained formulas for flood runoff ratio can be applied as an element for the estimation, peak discharge for the design of various hydraulics structures which can be concidented with meteorological and topographical condition. The obtained through this study were analyzed as follows. 1.It was found that the magnitude of runoff ratio depends on the amount of rainfall for all studying basins. 2.Empirical formulas 'for the runoff' ratio were derivated as 1- 2,707 Rt0.345, 1-1.691 Rt0.242 and 1-1.807 Rt0.227 at Dan Yang, Chung Ju and Yeo Ju watershed, respectively. 3.The magnitude of runoff ratio was appeared in the order of Dan Yang, Chung Ju, and Yeo Ju are located at upper, middle and lower portion of Nam Han rivet basin, respectively. 4.It was assumed that in general the more it rains, the lesser becomes the ratio of loss rainfall. Especially, the ratio of loss rainfall for Dan Yang, upper portion of river basin was shown as the lowest among three watersheds. Besides, the magnitude of that was appeared in the order of Chung Ju and Yeo Ju watershed located at middle, and lower part of river basin, respectively. 5.Relative and standard errors of runoff ratio calculated by empirical formulas were shown to be within ten percent to the observed runoff ratio in all watersheds. 6.It is urgently essential that the effect of antecedent rainfall have an influence on the next coming flood should be studied in near future.

• Journal of Environmental Science International
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• v.15 no.11
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• pp.1017-1025
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• 2006

This study was conducted to evaluate characteristic of water duality in coastal sea of Incheon using a multivariate analysis. The analysis data in coastal sea of Incheon was aquired by the NFRDI data which was surveyed from March 1997 to November 2003. Eleven water quality parameters were determined on each survey The results were summarized as follow : Water quality in Incheon coastal sea could be explained up to 64.62% by three factors which were included in loading of fresh water and nutrients by the land(36.98%), seasonal variation(16.19%), and internal metabolism (11.24%). The results of time series analysis by factor score, in case of factor 1, station 1 influenced by Han river was shown to high factor score and station 3 located by outer sea was shown to low factor score. In case of factor 2, station 1 was appeared to high variation and station 3 was appeared to low variation. The result of cluster analysis by station was classified into three group that has different water quality characteristics. Especially, station 1 which affected by Han river and station 4 which affected by sewage treatment plant was appeared to considerable water quality characteristics against other station. In yearly cluster analysis, three group was classified and water quality in 2003 years due to high precipitation was different to another year. It could be suggested from these results that it is important to control discharge of fresh water by Han rivet and sewage treatment plant for water quality management of coastal sea of Incheon.

• Journal of KSNVE
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• v.8 no.1
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• pp.57-74
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• 1998

This paper is concerned with a combination of experimental and analytical investigation aimed at identifying modeling errors, accounted for the lack of correlation between experimental measurements and analytical predictions of the modal parameters for lap joint panels. A nonlinearity vibration test methodology, initiated from the theoretical analysis, is suggested for measurements of dynamic stiffnesses in a lap joint using the rivet fastener. Based on the experimental evidence on discrepancies between measured and predicted frequencies, improved finite element models of the joint are developed using PATRAN and ABAQUS, in which the beam element size is evaluated from the joint stiffnesses readily determined in the test. The beam element diameter as a principal design parameter is tuned to match experimental results within the evaluated bound value. Frequencies predicted by the proposed numerical model are compared with frequencies measured by the test. Improved predictions based on this new model are observed when compared with those based on conventional modeling practices.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.6
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• pp.585-590
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• 2000

A hemolysin producing strain was isolated from Kum rivet estuary located in west part of Korea. In the process of identification the isolated strain was similar to V. mimicus but did not show characteristics of known Vibrio species; therefore, the strain was designated as Vibrio sp. D9 ( V. kumkang) tentatively and further identification study was carried out by comparing its bacteriological characteristics, Morphologically Vibrio sp. D9 was a typical straight roe with a polar flagellium. Among known Vibrio species no identical strains were found when using automatic bacteria identification system ($MicioLog^(TM)$system, release 4.0, Biolog Inc., USA) which evaluated the ability of metabolizing 95 kinds of carbon and nitrogen sources. Vibrio sp. D9 showed 18 and 13 different responses as compared to V. mimicus and V. cholerae, respectively. Clear hemolysis zones were observed with the strain against human and sheep blood agar plate, Hemolytic toxicity was confirmed by strong vascular permeability and fatal toxicity against mouse was also observed. Thus the strain was a pathogenic vibrio. Growth conditions for Vibrio sp. D9 were salinity of $0{\~}5.0{\%}$, pH of $6.4{\~}9.8$, temperature of $15{\~}41^{\circ}C$, respectively.

• Conservation Science in Museum
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• v.7
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• pp.11-24
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• 2006

Plate armour is an important cultural property that reflects the ancient weaponry and the manufacturing technology of ironware as they are. Among the kinds of iron armour, horizontal plate armour has been very rarely excavated, and there are a few artifacts in their unimpaired shape like the plate armour excavated from Mangisanseong. This report reviews the manufacturing technology of ancient plate armour through its radiograph using appliable nondestructive irradiation and scientific conservation treatment. The seven-tiered plate armour excavated from Mangisanseong has ring hinge to open and shut the right side neck guard. The readout result of radiograph proved iron safety guard of Godaepan (a plate that links neck plate and horizontal plate) and leather safety guard of the right armpit with plate overlap and perforation interval; perforations that seem to have linked shoulder strap on wearing the armour are also observed. In particular, it is identified that the perforation and riveting technique avoided the connection of more than three plates with a rivet. This is an important material to illustrate the best use of function of plate armour overcoming its limit.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.6
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• pp.491-498
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• 2016

Stress on plates may increase in the neighborhood the edges or the holes for rivets or bolts. Excessive stress concentration may lead to severe breakage of the plates. Thus, it is important to conduct optimization of arrangement of holes at the design stage. In this paper, accuracy of FEM analysis was examined for such stress concentration. By changing the hole size on a narrow plate, change of the stress concentration factor(K) was investigated. Additionally, the same experiment was conducted about series of multiple holes on plate to investigate interaction between the adjacent holes. Then, the FEM results were compared to the reference predictions respectively. Finally, a method by which simple stress concentrating situations can be optimized, will be suggested. This method was examined by FEM, and showed similar tendency with the expectation. Therefore, this method can be valuable when arranging the holes on a plate.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.9 no.1
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• pp.25-34
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• 2010

Fretting damage reduces fatigue life of the material due to low amplitude cyclic sliding and changes in the contact surfaces of strongly connected machine and structures such as bolt, key, fixed rivet and connected shaft, which have relative slip of repeatedly very low frequency amplitude. In this study, the fretting fatigue behavior of 7050-T7451 aluminum alloys used mainly in aircraft and automobile industry were evaluated. The plain fatigue test and fretting fatigue test under cyclic bending load carried out commercial bending fatigue tester and specially devised equipments to cause fretting damage. From these experimental work, the following results obtained: (1) The plain fatigue limit for stress ratio R=-l was about 151MPa. (2) In case of fretting fatigue, fatigue limit for stress ratio R=-l about 72MPa, the fatigue limit for R=0 about 81MPa, and the fatigue limit for R=0.3 about 93MPa. (3) The fatigue limit reduction rates by the fretting damage were about 52%(R=-1), 46%(R=0) and 38%(R=0.3) respectively. (4) The fatigue limit reduction rate decreased with stress ratio increase. In fretting bending test, as stress ratio increased, occurrence of initial oblique crack by fretting decreased or phased out, so that fracture surfaces were formed by plain fatigue crack occurrence, and such tendency was notable as stress amplitude increased. (5) Tire tracks and rubbed scars were observed in the fracture surface and contacted surface.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.5
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• pp.76-84
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• 2021

In this study, an optimal stiffness model of the C-frame, which was supporting the mold and tool load, was proposed to obtain quality self-piercing riveting (SPR) joining. First, the load path acting on the C-frame structure was identified using topology optimization. Then, a final suggested model was proposed based on the load path results. Stiffness and strength analyses were performed for a rivet pressing force of 7.3 [t] to compare the design performance of the final proposed model with that of the initial model. Moreover, to examine the reliability of continuous and repeated processes, vibration analysis was performed and the dynamic stiffness of the final proposed model was reviewed. Additionally, fatigue analysis was performed to ascertain the fatigue characteristics due to simple repetitive loading. Finally, stiffness test was performed for the final proposed model to verify the analysis results. The obtained results differed from the analysis result by 2.9%. Consequently, the performance of the final proposed model was superior to that of the initial model with respect to not only the SPR fastening quality but also the reliability of continuous and repetitive processes.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.11a
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• pp.155-156
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• 2023

In the case of steel door frames commonly found in general buildings, there are various assembly methods such as rivets, bolts, and welding, but the welding method is generally used. However, this welding joint method has many problems, such as distortion due to heat and damage due to external shock. In particular, when used as a fire door, problems may occur in the event of a fire due to distortion caused by heat from welding and the weak welded joint area. In the case of rivet or welded joints, when moved after assembly, joint loosening due to external shock may occur. Problems may arise where the bonding strength becomes weak. In addition, with the recent increase in high-rise buildings and larger buildings, when assembly is completed and brought to the site, a place is needed to store it, and in addition, there is a problem in that it has to be transported several times in small quantities to the installation site, which is another problem of time and cost loss. This is coming to the fore. In order to fundamentally solve this problem, we have researched and developed a non-welding door frame that can be assembled on site. We have researched and developed three assembly methods: screw-type, insert-type, and protrusion-type. Non-welded door frames are small in size and easy to package, making them advantageous for domestic and overseas exports.