• Journal of the Korean Geotechnical Society
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• v.19 no.4
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• pp.191-200
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• 2003

This paper presents the rheological properties of bitumen for reducing negative skin friction. The bitumen has been widely used due to both the cost and construction effectiveness. Also, it is well known that the use of bitumen for reducing negative skin friction renders the best results among other available methods. Three different modified bitumens were used for the testing programs. The physical tests include the penetration, the softening point and penetration index. The rheological tests include phase angle, complex modulus, creep tests and flow tests. The tests were conducted at four different temperatures(15, 30, 45 and 6$0^{\circ}C$) in order to simulate the field condition. The test results were analyzed using the phase angle, G$^*$/sin $\delta$, creep compliance and shear viscosity. The result of tests showed that the phase angle increased and G$^*$/sin $\delta$ decreased with the increase of temperature. The creep compliance increased as the loading time increased. The difference of the creep compliance is detected as the time and temperature are varied, however, the difference of the shear viscosity is not significant among the samples tested in this study. The rheological properties of the bitumen also showed that the physical testing method and the temperature dependant testing method are somewhat limited to showing and expressing the full rheological properties of the modified bitumen. The introduction of the time and the temperature dependent testing method is necessary to find out the full rheological properties of the modified bitumen.

• Journal of the Ergonomics Society of Korea
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• v.30 no.6
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• pp.757-764
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• 2011

Objective: The aim of this study was to provide a method to improve the compliance and reduce the time by reducing the workload during the model change work. Background: The enterprises are constructing the small quantity batch production system by increasing the number of model change and reducing model-changing. However, the compliance is low because the work is strenuous and high skills are needed, so the system management is facing with many difficulties. Method: After classifying the model change work according to the purposes(preparation, change and adjustment) with the target of mascara filling machine, element tasks time were measured and the motion analysis(therblig symbol) and REBA analysis were performed. The study incorporated 3 independent variables as the number of motion, REBA score and the element time. The dependent variable is the type of element work as preparation, change and adjustment. The statistical test was performed by one-way ANOVA(${\alpha}$ < 0.05). Results: For the preparation, the number of motions appeared in the order of Use(U), Transport Loaded(TL), and Position(P). The order appeared in change is Use(U), Release Load(RL), and Grasp (G). The adjustment appeared in the order of Position(P) and Use(U). The results of average motion time as the element work times divided by the number of motion appeared in the order of adjustment(1.85sec/motion), preparation(1.11sec/motion), and change(0.62sec/motion). The results of REBA showed that the average risk level of change and adjustment were medium, but 53.1% of change and 42.9% of adjustment were evaluated as high. Conclusion: Reducing the avoidance and improving the compliance of work could be expected if the job autonomy were improved by improving the working postures with high risk level. Application: It is expected to solve the problem of reducing the time of model change work in the small quantity batch production system. The future work is to carry out the improvement directions found in the results and compare the results after improvement.

• Journal of Ocean Engineering and Technology
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• v.4 no.1
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• pp.88-100
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• 1990

Among the test methods to evaluate stress-corrosion cracking(SCC) on the basis of fracture mechanics, constant displacement(bolt) loading method using modified-WOL specimen is practically convenient. In this test method, compliance formula is generally required to calculate load(consequently $K_{ISCC}$). There are many problems in using the analytic compliance formula to calculate $K_{ISCC}$, so we had proposed the experimental $K_{ISCC}$ evaluation technique in the previous report. This study has employed the slightly altered configuration of modified-WOL specimen made of weldable structural stee(BS360-50D). With these specimens, stress-corrosion tests have been performed in $H_2S$ gas saturated 20% HCl solution. Through the test, the problems as mentioned earlier have been discussed again, and the proposed evaluation technique has been verified. And the stress-corrosion cracks and hydrogen blisters have been investigated in the initiation step with the aids of metallurgical micrographs, SEM fractographs, and EPMA analysis. The inclusions segregated in the mid-thickness region traps hydrogen to produce the hydrogen blistering. The applied or residual stress does not contribute the occurrence of the blister. Hydrogen absorbed into the mid-thickness region is consumed to produce the blistering so that stress-corrosion crack could hardly be detected at that region. The stress-corrosion cracks initiate from the inclusions and propagate in radial pattern. And the initiation site is remote from the crack tip and is inclined from the crack plane, which is assumed to be caused by the triaxial stress and the amount of the absorbed hydrogen.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2002.04a
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• pp.353-360
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• 2002

The objective of this study is to develop a technique that analyzes the global behavior of frame structures with local cracks. The technique is based on frame analysis and uses the stiffness matrix of cracked frame element. An algorithm proposed here analyzes a frame structure with local transverseedge cracks, considering the effects of crack length and location. Stress intensity factors are employed to calculate additional local compliance due to the cracks based on linear elastic fracture mechanics theory, and then this local compliance is utilized to derive the stiffness matrix of the cracked frame element. In order to verify the accuracy and reliability of the proposed approach, numerical results are compared with those of Finite Element Method for the cracked frame element, and the effects of single crack on the behavior of truss structure are also examined.

• Journal of Navigation and Port Research
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• v.31 no.4
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• pp.295-307
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• 2007

The statistics of Korean Maritime Safety Tribunal and Japan Marine Accidents Inquiry Agency shows that the major muses of collision at sea are Improper lookout and Non-compliance with marine traffic rules. Those two muses are occupying more than 70% of collision, and it's clear that those muses are undoubtedly closely related to simple human error. In this paper we tried to find out the root muses of this kind of human error of OOWs(officers on watch) through risk identification method and studied how to tackle them via risk control theory. In conclusion, the measures studied in this paper could be applied to help OOWs avoid their own human error as well as be used in shipping company for their fleets' safety management.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.12
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• pp.3010-3017
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• 2000

For integrity evaluation of cracked or damaged structures, fracture toughness test results in ASTM are widely used. The fracture toughness values of the structures are used as an effective design criterion in nuclear plants and aircraft structures. Sometimes the difference of P-$\delta$ curve trend during the unloading /reloading cycle in the fracture toughness test using partial unloading compliance was observed. The phenomenon as a possible source of error in determining fracture toughness may be caused by the residual stress during unloading work-hardening and bucking of a specimen. Therefore, we evaluate the effect of bucking and compressive residual stress during the K-R and J-R testing using a finite element method.

• Journal of Ocean Engineering and Technology
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• v.1 no.2
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• pp.101-112
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• 1987

Fracture toughness characterization in the transition region is examined for heat-treated and ionnitrided Ni-Cr-Mo steel. After heat treatment for the specimens of Ni-Cr-Mo steel, organizations of specimens-specimens which are heat-treated and ion-nitrided for 4 hours at 500 .deg. C and 5 torr in 25%N/dub 2/-75%H/sub 2/mixed gas-, hardness variety, and X-ray diffraction pattern of the ion-nitriding compound layer are observed. Fracture toughenss test of unloading compliance method were conducted over the regions from room trmperature to -70.deg. C. The compound layer was consisted of r'=Fe/sub 4/N phase and ion-nitrided layer's depth was 200mm from surface. The transition regions of heat-treated and ion-nitrided specimens were about -30.deg. C and -50.deg. C, respectively. The transition region of ion-nitrided specimens is estimated less than that of heat-treated one, and this is the effect of ion-nitriding.

• Journal of Korean Critical Care Nursing
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• v.16 no.3
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• pp.73-86
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• 2023

Purpose : This study aimed to identify the factors affecting the quality of life of lung transplant patients. Method : The participants were patients who received lung transplants at a general hospital in City Y. Data were collected through structured questionnaires from June 2023 to August 2023. General characteristics, lung transplantation-related characteristics, quality of life, functional disability, treatment compliance, social support, anxiety, and depression-were measured. For data analysis, hierarchical multiple regression was performed using SPSS/WIN 29.0. Results : In the final model, quality of life was associated with income, self-help group attendance, functional disability, social support, treatment compliance, and anxiety and depression. Together, they explained 61.2% of the total variance in the results. Conclusion : Our findings suggest that improving lung transplant patients' quality of life requires active intervention in stress management to perform treatment instructions well, a social support system that can help them financially, and encouraging and participating in social activities as patients.

• Proceedings of the KIPE Conference
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• 2006.06a
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• pp.172-174
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• 2006

Nowadays, a Spot Welding system has been widely used in all kinds of industries and the common control method of the systeme is a simple current control using SCR. But, that kind of system is less effective than a current control method using inverter. So, it is constantly proposed that an improvement of hard ware and control method of spot welding system in compliance with technological advancement in power electronics. This paper deals with spot welding system using inverter. Especially, it deals with hard ware structure, features and output characteristics.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.1157-1160
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• 1996

Control of a biped robot which has compliant ankle joints is dealt in this paper. Simulated version of a human ankle joint is built using springs and mechanical constraints, which gives a flexibility of joint and compliance against the touching ground. The biped robot with compliant ankle joints proposed here gives a good contact between its sole and the ground and makes foot landing soft. As a result, installing force sensors for measuring the center of gravity of the biped becomes easier. A motor to drive an ankle joint is not needed which makes legs light. However, the control problem becomes more difficult because the torque of the ankle joint to put the biped in a desired walking gait cannot be provided from the compliant ankle joint. To solve this problem, we proposed a dynamic gait modification method by adjusting the position of a hip joint. Simulation results for the mathematical model of the SD-2 biped in the Ohio State University are given to show the validity of the proposed controller.