• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.697-703
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• 2008

Excessive water leakage phenomenon happens through damage of nation core zone of about 17,000 storage of water facilities or collapse of dam is worried, is being damaged or enforce dilapidated fill dam core zone's repair reinforcement. Example that use grouting method of construction considering construction and economic performance etc. recently by repair reinforcement way about defect of dam is increased. Permeation grouting method repair & reinforcement of fill dam countermeasure is preferred in nation. Do that is economical to decide these repair reinforcement effect and grouting effect estimation method that do not give damage to dam is effective. Therefore, observing electricity resistivity Survey change of dam since grouting reinforcement using Electric resistivity Survey inquiry of seismic survey method in this research, Wished to verify grouting effect whether is possible as Electric resistivity Survey, and study whether integrity of dam through repair reinforcement defined.

• Steel and Composite Structures
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• v.31 no.3
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• pp.261-276
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• 2019

The study investigates the free vibration of a nano-scale sandwich beam by an extended high order approach, which has not been reported in the existing literature. First-order shear deformation theory for steel skins and so-called high-order sandwich panel theory for the core are applied. Next, the modified couple stress theory is used for both skins and cores. The Hamilton principle is utilized for deriving equations and corresponding boundary conditions. First, in the study the three-mode shapes natural frequencies for various material parameters are investigated. Also, obtained results are evaluated for two types of stiff and soft cores and isotropic, homogenous steel skins. In the research since the governing equations and also the boundary conditions are nonhomogeneous, therefore some closed-form solutions are not applicable. So, to obtain natural frequencies, the boundary conditions are converted to initial conditions called the shooting method as the numerical one. This method is one of the most robust approaches to solve complex equations and boundary conditions. Moreover, three types of simply supported on both sides of the beam (S-S), simply on one side and clamp supported on the other one (S-C) and clamped supported on both sides (C-C) are scrutinized. The parametric study is followed to evaluate the effect of nano-size scale, geometrical configurations for skins, core and material property change for cores as well. Results show that natural frequencies increase by an increase in skins thickness and core Young modulus and a decrease in beam length, core thickness as well. Furthermore, differences between obtained frequencies for soft and stiff cores increase in higher mode shapes; while, the more differences are evaluated for the stiff one.

• Proceedings of the KSRS Conference
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• v.2
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• pp.702-705
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• 2006

Change detection is a core function of remote sensing. It can be widely used in public services such as land monitoring, damage assessment from disaster, analysis of city growth, etc. However, it seems that the change detection using satellite imagery has not been fully used in public services. For the person who is in charge of public services, it seems not to be ease to implement the change detection because various functions are combined into it. So, to promote the use of the change detection in public services, the standard, the process and the method for the change detection in public services should be established. And the software which supports that will be very useful. This study aims to promote the use of satellite imagery in public services by building up the change detection process which are suitable for general public services and developing the change detection software to support the process. The software has been developed using ETRI Components for Satellite Image Processing to support the interoperability with other GIS software.

• PNF and Movement
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• v.17 no.3
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• pp.451-461
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• 2019

Purpose: This study identified the effect of abdominal muscle contraction using changes in waist circumference for healthcare workers with back pain due to inadequate posture during working hours. Methods: In this study, we provided educational training focused on posture alignment and utilized waist circumference change sensors to induce the contraction of abdominal muscles as a method to address low back pain in healthcare workers. All 32 participants received the same training and then were assigned to two groups: wearing the keeping core band (CB) and not wearing the keeping core band (NCB). For the CB group, the waist circumference change sensor was applied for 6 weeks during working hours. Wilcoxon's signed-ranks test and paired t-tests were used to compare the differences between the groups. All statistical significance levels were set to α=0.05. Results: Trunk muscle endurance increased significantly in the CB group. There was no significant difference in stability index to evaluate static postural control, but active hip abduction tests, which evaluate dynamic postural control, showed significant decrease in the CB group. Conclusion: These results suggest that the induction of abdominal contraction using the waist circumference change sensor may improve the trunk muscle endurance and the postural control ability of the hip and pelvis of healthcare workers.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.6
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• pp.872-877
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• 2015

The Permanent Magnet (PM) machine used at speed control using field-weakening control method. But the field-weakening current, which reduces the field flux for high speeds, causes significant copper and core losses. Therefore, this paper deals with the PM performance evaluations in a pole changing memory motor (PCMM). The PCMM can change the number of magnetic poles and produce two types of torque. When the motor operates with eight poles, it produces a magnetic torque at low rotational speeds. When the motor changes to four poles, it produces both magnetic torque and reluctance torque at high speeds. The paper explain the principle and basic characteristics of the motor by using a finite element method magnetic-field analysis, which consists of a PM magnetized by a pulse d-axis current of the armature winding. The results of our experiment show that the proposed motor reduces core loss by 10% and 55% under no-load and load conditions, and doubles the speed range of the motor.

• Nuclear Engineering and Technology
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• v.52 no.11
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• pp.2431-2441
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• 2020

Currently, the pin-by-pin homogenized solvers are a very active research field as they can, unlike the nodal codes, directly predict the local power, while requiring significantly less computational resources than the heterogeneous transport codes. This paper presents a recently developed pin-by-pin diffusion/SP3 solver Tortin, its spatial discretization method and the reflector treatment. Regarding the spatial discretization, it was observed that the finite difference method applied on pin-cell size mesh does not properly capture the big flux change between MOX and uranium fuel, while the nodal expansion method is more accurate but too slow. If the finite difference method is used with a finer mesh in the outer two pin rows of the fuel assembly, it increases the required computation time by only 50%, but decreases the pin power errors below 1% with respect to lattice code reference solutions. The paper further describes the coupling of Tortin with a microscopic depletion solver. Several verification tests show that the SP3 pin-by-pin solver can reproduce the heterogeneous transport solvers results with very good accuracy, even for fuel cycle depletion of very heterogeneous core employing MOX fuel or inserted control rods, while being two orders of magnitude faster.

• Convergence Security Journal
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• v.7 no.2
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• pp.27-37
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• 2007

Companies have to take agility against change of environment and build up the capacity of new value creation in today's management environment. Until now, there are so many management method for efficiency of management, rationality of management and IT (information technology) supported this method by integration of enterprise task and process automation. but company's competitiveness through the efficiency of management realized the limitations recently. so companies needs the new management method to raise core value of enterprise. This study applies strategy intelligence which is some part of Business Intelligence. We can identify the core value driver by using this method. and the core value driver is connected the KPI (key performance indicator) of processes in BPM (Business Process Management). This help the management of process focused on value driver. and some part of activity driver that effect the process performance can be use the Six Sigma method to strategic business process. This study first introduces the concept of Business Intelligence, Business Process Management and Six Sigma. and then efficient connection plan for value based strategic business process is introduces.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.3
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• pp.115-125
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• 2008

Recently, Exhaust Gas Recirculation (EGR) system which re-flow a cooled exhaust gas from vehicles burning diesel as fuel to a combustion chamber of engine has been used to solve the serious air pollution. For the design and mass production of EGR system, it is essential to ensure structural integrity evaluation. The EGR system consisted of ten dimpled oval core rectangular tubes, two fix-plates, two coolant pipes, shell body and two flanges in this study. To confirm the safety of the designed system, finite element modeling about each component such as the dimpled oval core tube with the dimpled shape and others was carried out. The reliability of EGR system against exhaust gas flow with high temperature was investigated by flow and pressure analysis in the system. Also, thermal and strength analysis were verified the safety of EGR system against temperature change in the shell and tubes. Furthermore, modal analysis using ANSYS was also performed. From the results of FE analysis, there were confirmed that EGR system was safe against the flow of exhaust gas, temperature change in EGR system and vibration on operation condition, respectively.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2005.05a
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• pp.48-53
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• 2005

The world, coming into the 21st century, is preparing a new revolution called a knowledge-based society after the industrial society. The interest of the world is concentrated on information technology, nano-technology and biotechnology. In particular, the nano-technology of which study was originally started from an alternative for overcoming semiconductor micro-technology. It can be applied to most industry subject such as electronics, information and communication, machinery, chemistry, bioengineering, energy, etc. They are emerging into the technology that can change civilization of human beings. Specially, ultra precision machining is quickly applied to nano-technology in the field of machinery. Lately, with rapid development of electronics industry and optic industry, there are needs for super precision finishing of various core parts required in such related apparatuses. This paper handles stability of a super precision micro cutting machine that is a core unit of such a super precision finisher, and analyzes the results depending on the hinge type and material change, using FEM analysis. By reviewing the stability, it is possible to achieve the effect of basic data collection for unit control and to reduce trials and errors in unit design and manufacturing.

• Design & Manufacturing
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• v.13 no.2
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• pp.17-21
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• 2019

In this study, selective laser sintered 3D printing mold core and metal core were used to investigate the difference of the thickness shrinkage from the gate of the injection molded part at a constant interval. SLS 3D printing mold core was made of nylon-based PA2200 powder and the metal core was manufactured by conventional machining method. As the PA2200 powder material has low strength, thermal conductivity and high specific heat characteristics compared with metal, molding conditions were set with the consideration of molten temperature and injection pressure. Crystalline resin(PP) and amorphous resin(PS) with low melting temperature and viscosity were selected for the injection molding experiment. Cooling time for processing condition was selected by checking the temperature change of the cores with a cavity temperature sensor. The cooling time of the 3D printing core was required a longer time than that of the metal core. The thickness shrinkage of the molded part compared to the core depth was measured from the gate by a constant interval. It was shown that the thickness shrinkage of the 3D printing core was 2.02 ~ 4.34% larger than that of metal core. In additions, in the case of metal core, thickness shrinkage was increased with distance from the gate, on the contrary, in the case of polymer core showed reversed aspect.