• Journal of the Korea Convergence Society
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• v.10 no.11
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• pp.15-21
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• 2019

The fourth industrial revolution is noted. It is a smarter factory. At present, research on CNC (Computerized Numeric Controller) is actively underway in the manufacturing field. Domestic CNC equipment, acoustic sensors, vibration sensors, etc. This study can improve efficiency through CNC. Collect various data such as X-axis, Y-axis, Z-axis force, moving speed. Data exploration of the characteristics of the collected data. You can use your data as Random Forest (RF), Extreme Gradient Boost (XGB), and Support Vector Machine (SVM). The result of this study is CNC equipment.

• Journal of the wind engineering institute of Korea
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• v.22 no.4
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• pp.163-169
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• 2018

In this study, wind loads exerted on the offshore wind turbine rotor in parked condition were predicted with variations of wind speeds, yaw angles, azimuth angle, pitch angles, and power of the atmospheric boundary layer profile. The calculated wind loads using blade element theorem were compared with those of estimated aerodynamic loads for the simplified blade shape. Wind loads for an NREL's 5 MW scaled offshore wind turbine rotor were also compared with those of NREL's FAST results for more verification. All of the 6-component wind loads including forces and moments along the three axis were represented on a non-rotating coordinate system fixed at the apex of rotor hub. The calculated wind loads are applicable for the dynamic analysis of the wind turbine system, or obtaining the over-turning moment at the foundation of support structure for wind turbine system.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.4
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• pp.300-309
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• 2017

A spacecraft obtains a reaction momentum required for an orbit correction and an attitude control by exhausting a combustion gas through a small thruster in space. If the exhaust plume collides with spacecraft surfaces, it is very important to predict the exhaust plume behavior of the thruster when designing a satellite, because a generated disturbance force/torque, a heat load and a surface contamination can yield a life shortening and a reduction of the spacecraft function. The purpose of the present study is to ensure the core technology required for the spacecraft design by analyzing numerically the exhaust gas behavior of the 10 N class bipropellant thruster for an attitude control of the spacecraft. To do this, calculation results of chemical equilibrium reaction between a MMH for fuel and a NTO for oxidizer, and continuum region of the nozzle inside are implemented as inlet conditions of the DSMC method for the exhaust plume analysis. From these results, it is possible to predict a nonequilibrium expansion such as a species separation and a backflow in the vicinity of the bipropellant thruster nozzle.

• Journal of the Korea Concrete Institute
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• v.27 no.6
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• pp.615-623
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• 2015

The previous strut-and-tie models (STMs) to evaluate the shear strength of squat shear walls with aspect ratio less than 2.0 do not consider the axial load transfer of concrete strut and individual shear transfer contribution of horizontal and vertical shear reinforcing bars in the web. To overcome the limitation of the existing models, a simple STM was established based on the crack band theory of concrete fracture mechanics. The equivalent effective width of concrete strut having a stress relief strip was determined from the neutral axis depth and effective factor of concrete strength. The shear transfer mechanism of shear reinforcement at the extended crack band zone was calculated from an internally statically indeterminate truss system. The shear transfer capacity of concrete strut and shear reinforcement was then driven using the energy equilibrium in the stress relief strip and crack band zone. The shear strength predictions of squat shear walls evaluated from the current models are in better agreement with 150 test results than those determined from STMs proposed by Siao and Hwang et al. Furthermore, the proposed STM gives consistent agreement with the observed trend of the shear strength of shear walls against different parameters.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.6
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• pp.61-69
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• 2013

This research is aimed to evaluate characteristics and dynamic modeling of MR damper for semi-active vibration control. A MR damper of semi-active type was designed and made for the purpose of controlling the vibration of a real-size model structure. Usually a semi-active control system equipped with a MR damper requires a dynamic model which expresses numerical data about the damping capacity and dynamic characteristics generated by a MR damper. To fulfil the requirement, a Power model and a Bingham model were particularly employed among many dynamic models of MR damper. Those models being contrasted with other ones, a dynamic test was carried out on the developed MR damper. In the test, excitation frequencies were conditioned to be 0.15 Hz, 1.0 Hz, and 2.0 Hz, and three different currents were adopted for each frequency. From these test results, it was found that displacement affected control capacity of the MR damper. The test results led to the identification of model variables for each dynamic model, on the basis of which a force-speed relation curve and expected damping force were derived and contrasted to those of the developed MR damper. Therefore, it was proven that the MR damper designed and made in this research was effective as a semi-active controller, and also that displacement of 2mm at minimum was found to be secured for vibration control, through the test using various displacements.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.1
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• pp.9-20
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• 2019

The number of natural disasters in Korea, such as earthquakes, is increasing. As a result, there is growing need for temporary residences or shelters for disaster conditions. The aim of this study was to produce post-disaster refugees housing differentiated from existing shelters using lightweight composite panels. To accomplish this, the structural performance of lightweight composite panels was validated, and an in-plane shear strength test was conducted according to the ASTM E72 criteria among the performance test methods for panels. As a result of the experiment, the maximum load for each specimen under an in-plane shear load was determined. All the experiments ended with the tear of the panel's skin section. The initial stiffness of the specimens was consistent with that predicted by the calculations. On the other hand, local crushing and tearing, as well as the characteristics of the panel, resulted in a decrease in stiffness and final failure. Specimens with an opening showed a difference in stiffness and strength from the basic experiment. The maximum load and the effective area were found to be proportional. Through this process, the allowable shear stress of the specimens was calculated and the average allowable shear stress was determined. The average ultimate shear stress of the lightweight composite panels was found to be $0.047N/mm^2$, which provides a criterion of judgement that could be used to expect the allowable load of lightweight composite panels.

• The Journal of the Korea Contents Association
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• v.22 no.6
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• pp.453-466
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• 2022

This study attempted to examine the role of gender roles in psychological distress of Korean adult men. Specifically, it was attempted to verify whether compliance with multidimensional male gender roles predicts psychological distress through gender role conflict. To this end, this study was conducted on 358 male participants aged 19 to 39 using the Korean Conformity to Masculine Norm Inventory, Korean Male Gender Role Conflict Scale, and General Health Questionnaire. As a result of the study, it was found that the influence on psychological distress through male gender role conflict was different depending on the sub-factors of the male gender norm. The sub-factors of masculine norms, 'power and control', 'job - independence', and 'emotion suppression', were statically predicted psychological distress through the medium of 'fear for femininity', which is a sub-factor of gender role conflict. Meanwhile, among the male norms, 'male leadership' and 'family support' had negative direct effects on psychological distress, and the indirect effects through gender role conflict were not significant. The results of this study suggest that the sub-factors of male norms have different functions for psychological distress, and in particular, the dysfunctional role of male norms can be caused by negative emotions about femininity during gender role conflict.

• Korean Journal of Cognitive Science
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• v.15 no.4
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• pp.31-47
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• 2004

This study was carried out to examine the development of physical knowledge in children. Eighty children aged 3- to 11-year-old and 16 adults were participated in this study. Participants' knowledge about failing, sliding and sinking/floating objects was investigated to understand what kind of knowledge they had, whether their knowledge was organized as theory and what was the nature of the developmental change in physical knowledge. Results showed that, for falling object task children of all age had correct knowledge about object's falling phenomena. However, there were age differences in children's understanding of the cause of object's falling. As the children's age decreased, the frequency of explanation referring to the absence of supper rather than the gravity as the cause of falling phenomena increased. For the sliding object task, children of all age could predict the motion of sliding object correctly. But only a few 9- and 11-year-old children could understand the effect of object weight and relations between gravity, frictional force and their interactions. Children under age 7 showed no evidence of possessing these knowledge. For sinking or floating object task, children of all age and even adults showed difficulties in understanding the sinking or float phenomena per se. For the cause of these phenomena although a few 9- and 11-year-old children referred to buoyancy as the cause, they had no correct knowledge about the buoyancy. This was also true for the adults. As a conclusion, the results of this study suggested that, not 3, but as young as 5-year-old children's physical knowledge exited as a form of naive theory in terms of their use as a causal devise in explaining the cause of object motion. However, even the theory of 9- and 11-year-old children was lack of the abstractness and coherence, which were also important characteristics of a theory. Finally, developmental change in physical knowledge proceeded toward more frequent and consistent use of physical knowledge as causal device and more abstract and coherently organized theory.

• The Critical Review of Religion and Culture
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• no.31
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• pp.141-172
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• 2017

The objectives of this paper are to investigate hunting, stock raising, sacrifice recorded in the oracle bone inscriptions of Shang Dynasty. I want to raise two basic questions. First, what were the functions of hunting, stock raising, sacrifice, which constructed the world of life in Shang Dynasty? Second, what were the relationships of gods, men, animals derived from them? These questions are brought up to how the commoners of Shang Dynasty build the world and perceive it. I adopted positively prevalent theories for answering those questions. I am particularly provided with Michael J. Puett's insightful remarks in this presentation. He criticizes the previous viewpoint that the relationships of gods and men in ancient China were harmonious and mutually respondent. According to him, in the ancient way of thinking of China the world of gods was full of whimsical and unpredictable power and also contained the risks, which led to disaster to the human world. So it is needed to be controled in a certain way. The sacrifice and the divination must have been instruments for controlling it in ancient China. In the same vein his arguments can be applied to the special connotations of hunting and stock raising, by the benefit of which I developed my own ideas in this paper. The conclusions are as follows. First, Shang dynasty tried to suppress the latent danger of two worlds. The nature represented by animals and the world of gods were respectively considered as the unknown domains, which is to threatening human life. Hunting, stock raising, sacrifice were the ways and means of controlling these two domains of power, which cause chaos in life. Second, the relationships among gods, men, animals had various functions and changed their status role, depending on the circumstances. Hunting and stock raising were important methods to domesticate animals with violence. In this domestication process animals became "victims" but animals are also to be the messengers to gods through being slain in the sacrifice. In this way animals are both inferior and superior to men and hold a unique status between gods and men.

• Journal of the Korean Geotechnical Society
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• v.20 no.5
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• pp.99-107
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• 2004

Anisotropic characteristics of deformation are important to understand the particular behavior in the pre-failure state of soils. Recent experiments show that cross-anisotropic moduli of granular soils can be expressed by functions of normal stresses in the corresponding directions, which is closely linked to micromechanical characteristics of particles. Granular soils are composed of a number of particles so that the force-displacement relationship at each contact point governs the macroscopic stress-strain relationship. Therefore, the micromechanical approach in which the deformation of granular soils is regarded as a mutual interaction between particle contacts is one of the best ways to investigate the anisotropic elastic deformation of soils. In this study, a numerical program based on the theory of micromechanics is developed. Generalized contact model for the irregular contact surface of soil particles is adopted to represent the force-displacement relationship in each contact point far the realistic prediction of anisotropic moduli. To evaluate the model parameters, a set of analytical solutions of anisotropic elastic moduli is derived in the isotropic stress condition. A detailed procedure to determine the model parameters is proposed with emphasis on the practical applicability of micromechanical program to analyze the elastic behavior of the granular soils.