• Journal of Ocean Engineering and Technology
• /
• v.16 no.6
• /
• pp.55-59
• /
• 2002

Delamination means that cracking occurs on the interface layer between composite laminates. In this paper, to predict the delamination growth in composite laminates subjected to low-velocity impact, the unit load method was introduced, and an eighteen-node 3-D finite element analysis, based on assumed strain mixed formulation, was conducted. Strain energy release rate, necessary to determine the delamination growth, was calculated by using the virtual crack closure technique. The unit load method saves the computation time more than the re-meshing method. The virtual crack closure technique enables the strain energy release rate to be easily calculated, because information of the singular stress field near the crack tip is not required. Hence, the delamination growth in composite laminates that are subjected to low-velocity impact can be efficiently predicted using the above-mentioned methods.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.29 no.2
• /
• pp.33-39
• /
• 2015

Power supplying capacity of the distribution feeder should be maintained within thermal capacity of the wire. This paper presents the minimum spanning tree based load balancing technique to release multiple overloading of distribution feeders. In order to minimize number of involved backup feeders, Dijkstra and Prim algorithm are adopted to construct minimum spanning tree. Simulation testing result based on part of KEPCO's commercial distribution systems shows effectiveness of proposed scheme.

• Fire Science and Engineering
• /
• v.31 no.6
• /
• pp.16-22
• /
• 2017

In Korea, performance-based fire safety designs are being discussed to deal with the various risks of fire in complex and diverse types of structure. However, performance-based fire safety designs are not actively employed because it is difficult to estimate the fire characteristics related to the various factors in buildings. In this study, real scale fire tests were conducted based on fire severity levels and fire loads provided in He New Zealand Building Code, in order to use the results as guidelines and fundamental data for performance-based designs. In the real scale fire tests conducted in a 10MW full-scale calorimeter, wood cribs were placed in a $2.4(L){\times}3.6(W){\times}2.4(H)m$ mock-up of a compartment which had one $0.8(L){\times}2.0(H)$ opening for different fire loads and heating was continued until all of the wood cribs were burned down. The heat release rate started to increase rapidly 90 seconds after the wood cribs caught fire. In the test with a fire load level 1, the maximum heat release rate of 4743.4 kW was reached at 244 second. In the test with fire load level 2, a maximum heat release rate of 5050.9 kW was reached at 497 second. In the test with fire load level 3, a maximum heat release rate of 4446.9 kW was reached at 677 second.

• Proceedings of the KSME Conference
• /
• 2001.11b
• /
• pp.830-836
• /
• 2001

An one-zone heat release analysis was studied for a 4 cylinder indirect diesel engine. The object of the study is to calculate the heat release accurately including the effect of specific heat ratio, heat transfer and crevice volume and to find out combustion characteristics of an indirect diesel engine cosidering the effect of both pressure in the main and swirl chambers. The integrated gross heat release values were close to the measured fuel energy at various full load operating conditions.

• Environmental Engineering Research
• /
• v.10 no.5
• /
• pp.257-263
• /
• 2005

A batch and a continuous type experiments were conducted to test the conditions for simultaneous phosphorus release and uptake, and denitrification, taking place in one process. The bacteria able to denitrify as well as to remove phosphorus were evaluated for the application to biological nutrient removal(BNR) process. In the batch-type experiment, simultaneous reactions of phosphorus release and uptake, and also denitrification were observed under anoxic condition with high organic and nitrate loading. However the rate and the degree of P release were lower than that occurred under anaerobic condition. BNR processes composed of anaerobic-anoxic-oxic(AXO), anoxic-anaerobic-oxic(XAO) and anoxic-oxic(XO) were operated in continuous condition. The anoxic reactors in each process received nitrate loading. In the AXO process, P release in anaerobic reactor and the luxury uptake in oxic reactor proceeded actively regardless to nitrate loading. However in XAO and XO processes, P release and luxury uptake occurred only with the nitrate loading less than $0.07\;kg{NO_3}^--N$/kgMLSS-d. With higher nitrate load, P release increased and the luxury uptake decreased. Therefore, it appeared that the application of denitrifying phosphorus-removing bacteria (DPB) to BNR process must first resolve the problem with decrease of luxury uptake of phosphorus in oxic reactor.

• Journal of Advanced Marine Engineering and Technology
• /
• v.11 no.3
• /
• pp.31-44
• /
• 1987

Nowadays, the problems of energy and environmental pollution become serious day by day and the diesel engine, which has been proved to be superior to gasoline engine with respect to fuel consumption and ecological problems of exhaust gas, has been adopted widely for various purposes from the marine diesel engine and the dynamo engine to all kinds of engine on land. Therefore, extensive parametric studies on combustion of diesel engine should be done for its desing and improvement. To predict the behavior of diesel engien according to variable operating conditions by means of cycle simulation, the reasonable pattern of heat release rate has to be asumed. But it is necessary to know the actual variation of heat release rate in order to assume the reasonable pattern of heat release rate according to the actual operating conditions. In this paper, on a high speed small bore diesel engine with pre-combustion chamber, experimental investigations were carried out to determine the relationship between the heat release pattern and parameters such as engine load and speed. And also, the theoretical investigations about the performance variations of the above diesel engine according to the predicted pattern of heat release rate variation were performed. From the above observations, it may be said that the Fanboro indicator, which was used to get the cylinder pressure, can be used to estimate a reasonable pattern of heat release rate and it is confirmed that the pattern of heat release rate for the pre-combustion type engine is different from that of the direct injection type engine.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
• /
• v.27 no.2
• /
• pp.87-92
• /
• 2021

Purpose: This study aimed to investigate the effects of myofascial release technique on pain threshold and hormonal changes in patients with adhesive capsulitis of the shoulder. Methods: Eight patients with adhesive capsulitis were treated with the myofascial release technique. Myofascial release is a form of manual therapy that involves the application of a low load, long duration stretch to the myofascial complex, intended to restore optimal length, decrease pain, and improve function. Blood tests and pressure pain threshold (PPT) examinations were performed on their first visit. On their second visit, the myofascial release technique was applied to the shoulder for 20 min. Then, blood tests and PPT were re-evaluated to determine the effects of the myofascial release technique on pain threshold and hormonal changes. Results: Pain threshold increased from 2.92 to 24.13 lb after treatment. Epinephrine decreased from .13 to .08 ng/mL whereas norepinephrine increased from .25 to .41ng/㎖ after treatment. Conclusion: Myofascial release technique in patients with adhesive capsulitis increased pain thresholds, norepinephrine and decreased epinephrine levels.

• Journal of Advanced Marine Engineering and Technology
• /
• v.28 no.7
• /
• pp.1101-1110
• /
• 2004

An one-zone heat release analysis was applied to a 4 cylinder indirect injection diesel engine. The objective of the study is to calculate heat release accurately considering the effect of specific heat ratio. heat transfer and crevice model and to find out combustion characteristics of an indirect diesel engine considering the effect of the pressures in main and swirl chambers. Especially specific heat ratio indicating combustion characteristics is adapted. instead of that indicating matter properties, which has been used in former studies Moreover by adaption of blowby model, cylinder gas mass became accurately calculated. Therefore, with ideal gas equation, calculating cylinder gas temperature, it was found to affect heat transfer loss and heat release. Determining heat transfer constants $C_1$. $C_2$ as 0.6 respectively. the integrated gross heat release values were predicted well for the measured value at various engine speed, full load operating conditions. The curve of heat release rate was similar to SI engine rather than DI engine. That is originated from that swirl chamber reduce an instant combustion which occurs in DI engine due to ignition delay on early stage of combustion.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.19 no.2
• /
• pp.330-337
• /
• 1995

For a rotating body with cracks, the new energy release rate equation is presented. The derived equation is different from the other researcher's results. It is a path-independent integral which excluded the derivatives of displacements near the crack tip, thereby improving the numerical accuracy of the energy release rate computation. Moreover, as the equation was derived on basis of the energy principle and non-linear elasticity without assumptions, it can applied to the cracked body with arbitrary shape under elastic-plastic deformation. Several examples are treated to demonstrate the efficiency and accuracy of the proposed method compared to existing methods.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.4 no.4
• /
• pp.171-178
• /
• 1996

DCB(pure mode I) and CLS(mixed mode) tests were performed to investigate the effect of fracture mode on the interlaminar fracture of composite laminate. Mode I critical strain energy release rate was found to be $133J/m^2$ from the DCB test and total strain energy release rate decreased from $1, 270J/m^2$ as thickness ratio(tl/t) varied from 0.333 to 0.667 from the crease from the CLS test. Crack length had no effect on the total strain energy release rate and load was almost constant during the crack growth of the specimen which had the specific thickness ratio. Crack initiated when the stress of the strap ply reached constant stress $42kgf/mm^2$ which was found to be independent of the thickness ratio.