• Journal of Ocean Engineering and Technology
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• v.36 no.4
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• pp.243-250
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• 2022

Subsea power cables are subjected to various external loads induced by environmental and mechanical factors during manufacturing, shipping, and installation. Therefore, the prediction of the structural strength is essential. In this study, experimental and theoretical analyses were performed to investigate the axial stiffness of subsea power cables. A uniaxial tensile test of a 6.5 m three-core AC inter-array subsea power cable was carried out using a 10 MN hydraulic actuator. In addition, the resultant force was measured as a function of displacement. The theoretical model proposed by Witz and Tan (1992) was used to numerically predict the axial stiffness of the specimen. The Newton-Raphson method was employed to solve the governing equation in the theoretical analysis. A comparison of the experimental and theoretical results for axial stiffness revealed satisfactory agreement. In addition, the predicted axial stiffness was linear notwithstanding the nonlinear geometry of the subsea power cable or the nonlinearity of the governing equation. The feasibility of both experimental and theoretical framework for predicting the axial stiffness of subsea power cables was validated. Nevertheless, the need for further numerical study using the finite element method to validate the framework is acknowledged.

• Structural Engineering and Mechanics
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• v.85 no.6
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• pp.729-742
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• 2023

It is a recent attraction to the mechanical scientists to investigate state of wave propagation, buckling and vibration in the sport balls to observe the importance of different parameters on the performance of the players and the quality of game. Therefore, in the present study, we aim to investigate the wave propagation in handball game ball in term of mass of the ball and geometrical parameters wit incorporation of the viscoelastic effects of the ball material into account. In this regard, the ball is modeled using thick shell structure and classical elasticity models is utilized to obtain the equation of motion via Hamilton's principle. The displacement field of the ball model is obtained using first order shear deformation theory. The resultant equations are solved with the aid of generalized differential quadrature method. The results show that mass of the ball and viscoelastic coefficient have considerable influence on the state of wave propagation in the ball shell structure.

• Journal of Korean Society of Forest Science
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• v.17 no.1
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• pp.29-34
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• 1973

This study was performed for the purpose of determining the effects of distribution of the lateral earth pressure in the case of sloping backfills of being consisted of the idealized cohesionless fragmental masses. The displacements were classified as eight types by D_UBROVA (by patterns). B type among these has its turning point at the top of the wall, moves outwardly and is significant to gravitational structure because of its foundation elasticity which causes displacement. Therefore, it might be surely acknowledged that the resultant, follows; $$E=1/2{\cdot}rH^2\frac{sin(u-{\varepsilon})cos({\alpha}+{\varepsilon})}{cos(u+{\alpha})}{\cdot}cot(u+{\rho})(t/m^3)$$, is appropriate for applying it to the designing of the sand-catch dams. The results obtained are as follows: 1. Lateral earth pressure is proportional to the square of the wall heights. 2. The coefficient(K) is directly proportional to the sloping of backfill surface and inversely proportional to the displacement. 3. The distribution of the pressure looks like parabola, curve of second order (Fig. 5, b). 4. The distribution of the pressure strength looks like that of hydrostatic pressure (Fig. 5, c).

• Korean Journal of Applied Biomechanics
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• v.17 no.4
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• pp.201-208
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• 2007

The purpose of this study is to compare 4 different body punch types(type 1: a punch using a shoulder, type 2: a punch using a waist, type 3: a punch using lower extremities, and type 4: a punch with elbows by your side at chest level) in horseback-riding stance and establish suitable teaching theory and method, which would be a useful reference to Taekwondo instructors on the spot(in Taekwondo dojangs all around Korea). Five exhibition players from Korean national Taekwondo exhibition team participated in this study. Each participant was asked to perform the four different types of punches and their kinematic and kinetic data were recorded with 7 vicon cameras(125Hz) and two force plates(AMTI, 1200Hz). We analyzed displacement, time, resultant center of body mass trajectory, velocity, trunk angular velocity, and ground reaction force(GRF) from each body segment in body punch and the result. I performed 1-way ANOVA(RM) for average values of each player after standardization and statistical significance was set as p<.05. was as the following ; First, they showed a tendency to take the body punch posture with the biggest motion at a shoulder and on descending order a waist and a knee. Second, a mean time for each body punch on ascending order 0.46sec. for type 2, 0.49sec for type 3, 0.50sec. for type 4, and 0.56sec. for type 1. Third, a mean resultant center of body mass trajectory for each body punch the longest 4.07cm for type 3 and the shortest 2.458cm for type 1. Fourth, a mean of maximal velocity of a fist strike was the fastest 5.99m/s for type 3, 5.93m/s for type 4, 5.67m/s for type 2, and 5.01m/s for type 1 on the descending order. Fifth, a mean of maximal trunk angular velocity of the fastest 495.6deg./sec. for type 4 and 337.7deg./sec. for type 1 on the descending order. Sixth, strongest value was type 3, 2 for anterior-posterior ground reaction force(left -54.89N, right 60.58N), type 4 for medial-lateral GRF(left 83.59N, right -80.12N), and type 3 for vertical GRF(left 341.79N, right 426.11N).

• Journal of the Korean Geotechnical Society
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• v.22 no.8
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• pp.119-127
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• 2006

Granulated Blast Furnace Slag (GBFS) is produced in the manufacture process of pig-iron and shows a similar particle formation to that of natural sea sand and also shows light weight, high shear strength, well permeability, and especially has a latent hydraulic property by which GBFS is solidified with time. Therefore, when GBFS is used as a backfill material of quay or retaining walls, the increase of shear strength induced by the hardening is presumed to reduce the earth pressure and consequently the construction cost of harbor structures decreases. In this study, using the model sand box (50 cm$\times$50 cm$\times$100 cm), the model wall tests were carried out on GBFS and Toyoura standard sand, in which the resultant earth pressure, a wall friction and the earth pressure distribution at the movable wall surface were measured. In the tests, the relative density was set as Dr=25, 55 and 70% and the wall was rotated at the bottom to the active earth pressure side and followed by the passive side. The maximum horizontal displacement at the top of the wall was set as ${\pm}2mm$. By these model test results, it is clarified that the resultant earth pressure obtained by using GBFS is smaller than that of Toyoura sand, especially in the active-earth pressure.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.1049-1052
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• 2008

Coupling beams have been used in bearing wall system during last decades. Practically their sectional effects are fully considered in analysis stage to control lateral displacement because they have good contribution to the stiffness of bearing wall system. But the high resultant forces of coupling beam are not fully satisfied in design stage because coupling beams are restricted in sectional size. In this paper the performance of bearing wall system with coupling beam has been evaluated based on improved equivalent linearization procedure of FEMA 440. 15 storied building is selected for analysis. Variables for performance evaluation are natural period, degree of coupling and soil site. To evaluate performance, demand capacity spectrum is calculated based on KBC 2005. As a result, for the most of the cases the life safety limit of chord rotation of coupling beam is less than the performance point of system for soil site $S_D$. That means that the coupling beam can be severly damaged before the system reaches at performance point.

• The Journal of Korean Academy of Prosthodontics
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• v.33 no.4
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• pp.780-806
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• 1995

The purpose of this study was to describe the application of 3D finite element analysis to determine resultant stresses on the bone anchored fixed prosthesis, implants and supporting bone of the mandible according to fixture numbers and load conditions. 4 or 6 fixtures and the bone anchored fixed prosthesis were placed in 3D finite element mandibular arch model which represents an actual mandibular skull. A $45^{\circ}$ diagonal load of 10㎏ was labiolingually applied in the center of the prosthesis(P1). A $45^{\circ}$ diagonal load of 20㎏ was buccolingually applied at the location of the 10mm or 20mm cantilever posterior to the most distal implant(P2 or P3). The vertical distribution loads were applied to the superior surfaces of both the right and the left 20mm cantilevers(P4). In order that the boundary conditions of the structure were located to the mandibular ramus and angle, the distal bone plane was to totally fixed to prevent rigid body motion of the entire model. 3D finite element analysis was perfomed for stress distribution and deflection on implants and supporting bone using commercial software(ABAQUS program. for Sun-SPARC Workstation. The results were as follows : 1. In all conditions of load, the hightest tensile stresses were observed at the metal lates of prostheses. 2. The higher tensile stresses were observed at the diagonal loads rather than the vertical loads 3. 6-implants cases were more stable than 4-implants cases for decreasing bending and torque under diagonal load on the anterior of prosthesis. 4. From a biomechanical perspective, high stress developed at the metal plate of cantilever-to-the most distal implant junctions as a consequence of loads applied to the cantilever extension. 5. Under diagonal load on cantilever extension, the 6-implants cases had a tendency to reduce displacement and to increase the reaction force of supporting point due to increasing the bendign stiffness of the prosthesis than 4-implants cases. 6. Under diagonal load on cantilever extension, the case of 10mm long cantilever was more stable than that of 20mm long cnatilever in respect of stress distribution and displacement. 7. When the ends of 10mm or 20mm long cantilever were loaded, the higher tensile stress was observed at the second most distal implant rather than the first most distal implant. 8. The 6-implants cases were more favorable about prevention of screw loosening under repeated loadings because 6-implants cases had smaller deformation and 4-implants cases had larger deformation.

• Korean Journal of Applied Biomechanics
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• v.15 no.1
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• pp.237-257
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• 2005

It was to study as a following-research of "A Case Study on Center of Gravity(COG) Analysis when Performing Uchimata(inner thigh reaping throw) by Posture and Voluntary Resistance Levels(VRL) of Uke in Judo[I]". The purpose of this study was to analyze the COG variables when performing uchimata(inner thigh reaping throw) by two postures and voluntary resistance levels(VRL) of uke(reciver) in Judo. The subjects, who were one male judoka(YH) for 1992 Barcelona Olympic Games Olympian(silver medalist), and one male trainee; Y.I.University representative member (SDK), and were filmed on two S-VHS 16mm video cameras(60fields/sec.) through 3-dimensional motion analysis methods, that postures of uke were shizenhontai (straight natural posture) and jigohontai(straight defensive posture), VRL of uke were 0% and 100%, respectively. The kinematical variable was COG variable, distance of COG, and distance of resultant COG between uke and tori(the thrower), velocity and acceleration of COG. The data of this study collection were digitized by SIMI Motion Program computed the mean values and the standard deviation calculated for each variables. When performing uchinmata according to each posture and VRL of uke and classifying. From the data analysis and discussion, the conclusions were as follows : 1. Displacement of COG Subject YH, COG was the highest in kuzushi(balance -breaking), vertical COG was low when following in tsukuri(positioning; set-up), kake(application; execution), and COG was pattern of same character each postures and resistance, respectively. Subject SDK, COG was low from kumikata(engagement positioning) to kake, and COG was that each postures and resistance were same patterns, respectively. Subject YH, SDK, each individual, postures and resistance, vertical COG was the lowest in kake phase, when performing. 2. Distance of COG between uke and tori The distance of COG between uke and tori when performing, subject YH was $0.64{\sim}0.70cm$ in kumikata, $0.19{\sim}0.28cm$ in kake, and SDK was $0.68{\sim}0.72cm$ in kumikata, $0.30{\sim}0.42\;cm$ in kake. SDK was wider than YH. 3. Distance of resultant COG between uke and tori The distance of resultant COG between uke and tori when performing, subject YH was $0.27{\sim}0.73cm$ from kumikata to kake. and SDK was $0.14{\sim}0.34cm$ in kumikata, $0.28{\sim}0.65cm$ in kake. Jigohontai(YH:$0.43{\sim}0.73cm$,SDK:$0.59{\sim}0.65cm$) was more moved than shizenhontai(YH:$0.27{\sim}0.53cm$, SDK: $0.28{\sim}\;0.34cm$). 4. Velocity of COG The velocity of COG when performing uchimata, subject YH was fast anterior-posterior direction in kuzushi, ant.-post. and vertical direction fast in tsukuri and kake. SDK was lateral, ant.-post. and vertical direction in kuzushi, ant.-post. and vertical direction in tsukuri and ant.-post. direction in take, respectively. 5. Acceleration of COG The acceleration of COG when performing uchimata, The trend of subject YH was showed fast vertical direction in kuzushi and tsukuri, ant.-post. and vertical direction fast in kake. The trends of SDK showed lateral direction in kuzushi, lateral and ant.-post. direction in tsukuri and ant.-post. direction in kake, respectively.

• Journal of Energy Engineering
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• v.26 no.2
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• pp.1-11
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• 2017

While they are becoming more viable, synthetic natural gas (SNG) plants, with their high temperatures and pressures, are still heavily dependent on advancements in the state-of-the-art technologies. However, most of the current work in the literature is focused on optimizing chemical processes and process variables, with little work being done on relevant mechanical damage and maintenance engineering. In this study, a combination of pipe system stress analysis and detailed local stress analysis was implemented to prioritize the inspection locations for main pipes of SNG plant in accordance to ASME B31.3. A pipe system stress analysis was conducted for pre-selecting critical locations by considering design condition and actual operating conditions such as heat-up and cool-down. Identified critical locations were further analyzed using a finite element method to locate specific high-stress points. Resultant stress values met ASME B31.3 code standards for the gasification reactor and lower transition piece (bend Y in Fig.1); however, it is recommended that the vertical displacement of bend Y be restricted more. The results presented here provide valuable information for future risk based maintenance inspection and further safe operation considerations.

• Research in Community and Public Health Nursing
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• v.6 no.2
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• pp.319-334
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• 1995

To investigate the risk factors of low back pain, an epidemiological study was carried out among male workers aged 20-55 employed in an automobile industry in Korea during the time period from February 1993 to October 1995. Workers participated to this study were divided into low back pain group(LBP) and control group, according to the self-reports by written questionnaires. General characteristics, medical history, work related factors, fatigue, and MMPI were compared between two groups. To clarify the relationship between job related low back pain and radiologic features of lumbar spine, radiographic study was carried out. The resultant data were processed for $x^2-test$, t-test, and stepwise logistic regression to confirm the adjusted odds ratios. The results were as follows: 1. History of back disease, lifting and carrying work, excessive physical fatigue, and weakend back strength of individual workers were directly associated with low back pain. Odd ratios of these 4 risk factors of low back pain were 5.07, 3.34, 1.49, and 1.22 respectively. 2. The frequency of low back pain history was significantly higher in LBP group. 3. Back muscle strength of lumbar spine of LBP group were significantly lower than control group. 4. The workers in LBP group revealed high fatigue symptoms. 5. In MMPI test LBP group showed higher scales in hypochondriasis, depression, hysteria, psychopathic deviate, paranoia, psychasthenia, schizophrenia, and hypomania. 6. LBP group were more frequently involved in lifting and carrying, working in awkward position, bending, twisting and using lower extremities. 7. LBP group were exposed more to vibration during working. 8. In the Analysis of radiographs of lumbar spine, Jacob's line not crossing fourth lumhar disc space, transitional vertebrae and lumbar displacement more than 4.4mm in standing lateral view were more frequently observed in LBP group than control group. Through these results, it is concluded that identification of previous history of back problem, change of work or working environment for workers with previous back problem and measures to relieve both physical and psychological fatigue of the workers are required for optimal management of work-related back problems among workers. In the present study, several results were different from the previous reports: Jacob's line not corssing fourth lumbar disc space, lumbarization, and vertebral slipping (spondylolisthesis) more than 4.4mm are related to backache. Meticulous studies are required to elucidate the difference.