• KSCE Journal of Civil and Environmental Engineering Research
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• v.7 no.2
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• pp.141-153
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• 1987

The prediction of the exact behavior of multistory building is one of the most complicated problem encountered in structural engineering practice. An efficient computer method for the three dimensional analysis of building structures is presented in this paper. A multistory building is idealized as an assemblage of a series of rectangular plane frames interconnected by rigid floor diaphragms. The matrix condensation technique is employed for the reduction of degrees of freedom, which results in a significant saving in computational efforts and the required memory size. Kinematical approach was used to assemble condensed stiffness matrices of plane frames into a three dimensional stick model stiffness matrix. The static analysis follows the modified tridiagonal approach. Since this procedure utilizes the condensed stiffness matrix of the structure, the dynamic equations of motion for the story displacement are developed by assigning proper mass for each story. Analysis results of several example structures are compared to those obtained by using the well-known SAP IV for verification of the accuracy and efficiency of the computer program PFS which was developed utilizing the method proposed in this study. The analysis method proposed in this study can be used as an efficient and economical means for the analysis of multistory buildings.

• Journal of the Korea Society for Simulation
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• v.25 no.4
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• pp.53-63
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• 2016

This study aims to verify the feasibility of design by developing pressure flow-controlled swash plate type pump with the use of SimulationX, a computer analysis program. Developing analysis model based on design drawing data has a cost-saving effect because it is possible to figure out the effectiveness of design through the work and it never falls into repeated inaccuracies in the production process. Analysis model is developed in the following order. First, the structure of each part such as valve and rotating unit which have dynamic factor is analyzed and the modeling of single component is carried out, reflecting drawing data. Second, the modeling of pump assembly is carried out with the combination of each analysis model and a work is conducted to determine whether the modeling can perform pressure flow control function according to load condition smoothly based on design intent. At the end of the modeling process, the feasibility of design is verified by showing the parts which are moving as expected mechanism.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.3
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• pp.312-317
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• 2015

Seafarers can confront to evacuate from the ship with many reasons such as collision, grounding and fire accident. It believes that evacuation time from ship is very important element in order to increase survival rate in the contingency circumstance, however narrow and complex structure of ship is one of obstacle element against prompt evacuation. Taking into consideration the unique structure of ship compared to the structure of other facilities, speed of fire propagation on board ship is faster than the same size of other type facilities. Therefore, measures to prompt evacuation are required. But it comes with the behavioral constraints of the crews and passengers of the nature of operating in a complex structure with narrow vessels. Therefore, in this study, we propose a formula to be analyzed by theoretical approach and simulation methods to improve the survival rate for the crew and passenger of the ship through the ship's structural modification. We analyzed the temperature rise and visibility which are the most influential effects on the life safety in the event of fire by using a three-dimensional analysis of sight-only program Fire Dynamic Simulator (FDS) as analytical tools.

• Journal of Korean Society of Forest Science
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• v.103 no.3
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• pp.503-509
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• 2014

The purpose of this study was to investigate the effect of Forest-walking exercise on gait pattern in the elderly. The subjects (n=37) were assigned to 2 groups: Forest-walking exercise (FWE) group (n=19, $66.34{\pm}4.31$ years old) and In-door treadmill-walking exercise (ITWE) group (n=18, $67.18{\pm}2.78$ years old). The subjects participated in FWE program or ITWE program (3 times/week, 80 min/day) for 12 weeks. The subjects were tested on functional fitness (strength, endurance, agility/balance, BMI) and gait pattern (cadence, velocity, and stability) at the beginning and the end of the 12-weeks program. For data analysis, mean and standard deviation scores were calculated, and independent t-test and repeated two-way ANOVA were used. The results of this study were as follow: First, FWE group was significantly more improved than ITWE group on functional fitness(lower-body muscular strength, lower-body flexibility, mobility, cardiorespiratory endurance) after 12-weeks exercise program. But both groups showed equally improvements on functional fitness (upper-body muscular strength, upper-body flexibility, BMI). Second, FWE group was significantly more improved than ITWE group on cadence, gait velocity, and gait stability after 12-weeks exercise program. Therefore, this study may suggest that Forest-walking exercise based on sensory-motor functional integration improves efficiently functional fitness and gait pattern in the elderly, and further becomes an effective exercise method that makes more dynamic life, and prevents from falling.

• The Journal of the Korean Institute of Forest Recreation
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• v.22 no.4
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• pp.1-9
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• 2018

This study aimed to improve the quality of forest healing program through analyses of the program activities given at National Healing Forest and surveys conducted by Korea Forest Service. 99 DB data of the healing forest that were surveyed by KFS (August 2015~April 2016) were collected in order to affirm the activities. We analysed DB based on the format of the survey by target, 6 healing factors, location, season, time periods, operation hours and multifaceted evaluation. The results showed that the activities in the forest healing program targeted general public and the factor that was considered the most was psychotherapy factor. Healing forest trails were used as a location, spring, summer and fall as season, morning and afternoon as time period for the majority of the activities. The running time was 60 minutes. The multifaceted evaluation revealed that dynamic activities were preferred the most in development of programs. According to the results of the forest healing programs, it seems to be critical to enhance forest healing instructors' diversified professionalism. However, this will only be achievable once further investigations regarding forest healing effects by types of illnesses are conducted and provide solid foundation for such professionalism.

• Journal of the Korean Society of Radiology
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• v.9 no.5
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• pp.323-329
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• 2015

This study is aimed at assessing whether dynamic wedge filters are appropriate to be used instead of physical wedge filters. The X-ray energy generated from linear accelerator is commercialize 6 MV and 10 MV. $15^{\circ}$, $30^{\circ}$, $45^{\circ}$, and $60^{\circ}$ of physical wedge filter was irradiated by dose rate 100, 200, 300, 400, 500, and 600 MU/min for each angle and for comparison with a dynamic wedge filter, irradiate 96 times under the same conditions. The measurement conditions are as 100 cm source-film distance and $10{\times}10cm$ irradiated surface. A developed film was scanned and analyzed after a calibration through a dose analysis program and the dose rate was compared after calculating the standard deviation. Dynamic wedge filters make dose, scattered rays and treatment time reduced and very useful due to less irradiated doses to patients. The errors at each dose rate under the same conditions were irrelevant. Thus, treatment based on a high dose rate depending on the patient is expected to be feasible.

• The Journal of the Convergence on Culture Technology
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• v.1 no.3
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• pp.47-68
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• 2015

The purpose of this study was to clarify what's the middle-aged experience until now and what's the middle-aged women shed light on their life. The phenomenology study design was used and Giorgi method was used for this analysis. We selected 7 middle-aged women for this study such as 2 professor, 1 dentist, 1 own-business woman, 1 house house wife, 1 Nurse, and 1 farming woman. The result of this study were as followers; there were 7 structure factors such as 'poor family economic status', 'meaning of family-of-origin', 'dynamic social experience', 'marriage', 'heartrending', 'getting feeling of aging', and 'focus of life'. According to the results of this study, the participants who were more positive feeling of their poor family status, they were more becoming professional job in the adult age. And they shed light on their life with spirituality through the dynamic social experience, marriage, and heartrending. Therefore we suggest that right spiritual program for the better old aged time for them.

• Steel and Composite Structures
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• v.24 no.2
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• pp.227-237
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• 2017

This paper presents optimization of a long-span portal steel frame under dynamic wind loads using a surrogate-assisted evolutionary algorithm. Long-span portal steel frames are often used in low-rise industrial and commercial buildings. The structure needs be able to resist the wind loads, and at the same time it should be as light as possible in order to be cost-effective. In this work, numerical model of a portal steel frame is constructed using structural analysis program (SAP2000), with the web-heights at five locations of I-sections of the columns and rafters as the decision variables. In order to evaluate the performance of a given design under dynamic wind loading, the equivalent static wind load (ESWL) is obtained from a database of wind pressures measured in wind tunnel tests. A modified formulation of the problem compared to the one available in the literature is also presented, considering additional design constraints for practicality. Evolutionary algorithms (EA) are often used to solve such non-linear, black-box problems, but when each design evaluation is computationally expensive (e.g., in this case a SAP2000 simulation), the time taken for optimization using EAs becomes untenable. To overcome this challenge, we employ a surrogate-assisted evolutionary algorithm (SAEA) to expedite the convergence towards the optimum design. The presented SAEA uses multiple spatially distributed surrogate models to approximate the simulations more accurately in lieu of commonly used single global surrogate models. Through rigorous numerical experiments, improvements in results and time savings obtained using SAEA over EA are demonstrated.

• Journal of the Korean Geotechnical Society
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• v.21 no.1
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• pp.93-103
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• 2005

Both static pile load test with load transfer measuring system and the pile dynamic load test are performed to estimate the skin friction and behavior characteristics of a large drilled shaft. And the numerical modeling of large drilled shaft is performed by applying the FDM program. Since the magnitude of friction resistance depends on the relative displacement between soil and shaft, load and displacement at the arbitrary depth along the large drilled shaft are estimated to analyze the correlation. According to the measuring results of load transfer, unit skin friction along the large drilled shaft was fully mobilized at gravel layer in the middle of shaft and the frictional resistance transmitted to bedrock was relatively small. Also, even for the same drilled shaft, the results of PDA and static load test are different with each other and the difference is discussed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.3
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• pp.275-282
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• 2015

Recently, Vecna BEAR type robot to save injured individuals from inaccessible areas has been developed to minimize the loss of life. Because this robot is driven on rough terrain, there is a risk of rollover and vibration, which could impact the injured. In order to guarantee its stability, an algorithm is required that can estimate the speed limits for various environments in real time. Therefore, a dynamic model for real-time analysis is needed for this algorithm. Because the tracks used as the driving component of Vecna BEAR type robot consist of many parts, it is impossible to analyze the multibody tracks in real time. Thus, a lumped track model that satisfies the requirements of a short computation time and adequate accuracy is required. This study performed lumped track modeling, and the traction force was verified using RecurDyn, which is a dynamic commercial program.