• 한국전자통신학회논문지
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• 제11권10호
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• pp.935-940
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• 2016

최근 무선 전력 전송 시스템은 조명 분야뿐만 아니라 전기 자동차, 스마트폰 무선 충전 시스템 등 다양한 분야에서 기술이 점차 확대 적용되고 있다. 무선 전력 전송 시스템의 전력 전송 효율을 판가름 하는 가장 큰 두가지 요소로는 전력을 무선으로 전달하는 매개체인 송, 수신 코일부와 전력을 증폭하는 전력 증폭기부가 해당된다. 본 논문에서는 고효율 무선 전력 전송 시스템을 구축하기 위해 6.78MHz에서 동작하는 고효율 전력 증폭기 설계 방안과 공진 코일 제작 방법에 대해 소개한다.

• 건축역사연구
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• 제16권3호
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• pp.95-114
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• 2007

Since the 17th century, the society of Joseon dynasty belongs to a period of rapid transition in many fields. As the building is a result to be produced on the basis of a society and economy, the general transition in a society is to be reflected into a process of building construction. Especially, a study on the material supply system of economic base in a process of building construction is one of vely important factors in an understanding or estimate of a building. On the premise, this paper is to examine the supply system of iron materials and the tools in the construction of the government managed buildings in the late of Joseon dynasty on a viewpoint of productivity. Construction reports and other documents in those days are examined for the study. Following conclusions have been reached through the study. 1) The general supply method of iron materials for a large-scale government construction was based on 'byulgong', that is, a kind of tribute. 2) Various methods were selected in the supply method of iron materials for government use in the late of Joseon dynasty. The priority order of choice in its government policy was put on an easiness of amount security, on a minimum of expenditure, and on an efficiency of construction execution. 3) The manufacturing technique of weaponry was used in the production method of iron materials and the tools for government use. The cooperation of the official, the army, and the merchant had improved the manufacturing technique of building construction.

• 대한기계학회논문집A
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• 제21권6호
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• pp.988-994
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• 1997

The demands for robotic and automatic system are continually increasing in manufacturing fields. There have been many studies to monitor and predict the system, but they have mainly focused upon measuring cutting force, and current of motor spindle, and upon using acoustic sensor, etc. In this study, digital image of time series sequence was acquired by taking advantage of optical technique. Mean square error was obtained from it and was available for useful observation data. The parameter was estimated using PAA(parameter adaptation algorithm) from observation data. AR(auto regressive) model was selected for system model and fifth order was decided according to parameter estimation. Uncorrelation test was also carried out to verify convergence of parameter. Through the proceedings, it was found that there was a system stability.

• 한국임상보건과학회지
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• 제2권2호
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• pp.126-132
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• 2014

Purpose. Because traditional statistics approach had limitations in learning future forecasting and major factors causing occupational injuries in each industry, this paper develops a model forecasting and evaluating occupational injury rate by using a system dynamics model through the analysis of the industry injury statistics and the project for industry injury prevention. Method. The model of this paper consists of 12 total models such as a model of employees, of industrial disaster victims, of injury rate, etc.; In the analysis of firm size, it is classified and developed according to 12 groups on the basis of the number of employees, and in the analysis of industrial classification, it is done according to 10 total business fields such as manufacturing business, construction one, etc. Results. This paper suggests the methodology which forecasts industry injury rate by business field and size on the basis of developed model, and evaluates an industry injury prevention project from various angles. Conclusions. This paper deduced problem through the analysis of an industry injury by business fields and a comparative analysis of foreign cases, and analyzed to affect industry injury prevention by industry. And it also analyzed actual condition of industry injury, and did a difference in the level of safety consciousness according to the general characteristics of workers and occupational safety and health education related characteristics. In result, this paper suggests that analyzing occupational injury related factors, a safety budgetary allocation, and industry injury related factors can reduce illness costs such as employees' injury and medical care, and also assist cost for a disability.

• 한국기계가공학회지
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• 제5권2호
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• pp.49-55
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• 2006

In the consideration of the problem occurred by certain return bender brazing welding works that depend only on handworks, the automatization of the whole production line is impossible due to the high dependency of skillful workers. In addition, it is difficult to establish a standardization due to the various heat exchanger model and irregular amount of orders, and the fault reduction is also impossible due to the severe difference in brazing conditions. It is necessary to develop a method, which quantitively analyzes the problem existed in this manual brazing welding of return benders and technically solves that problem, and to lead the improvement of the productivity and cost reduction in order to increase the business competitive power. Then, this will contribute the technical development of automatic welding for Korea's heat exchanger businesses. Thus, this study develops an automatic technology, which automatically controls the flame strength using digital control methods, for various models and produces a sample model. It is possible to increase the productivity and produce uniformed and qualified products by solving the problem existed in manual processes using the developed automatic return bender brazing system. In addition, the brazing condition can be automatically controlled according to the model and line speed, and such an economical operation can reduce the production cost. The developed system is expected to future applications not only heat exchangers in the field of refrigeration and air conditioning, but also other various industrial fields that apply heat exchangers, such as car and boiler industries.

• International Journal of Naval Architecture and Ocean Engineering
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• 제9권2호
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• pp.219-226
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• 2017

These days, the great part of design processes in the field of ship or offshore manufacturing are planned and implemented using the CAD system customized for shipbuilding companies. It means that all information for design and production could be extracted and reused at the other useful fields which need cost considerable time and efforts. The typical example is the field of welding material quantity evaluation which is demanded during the construction of ship or offshore structures. The proper evaluation of welding material to be used and the usage of them at the stage of schedule planning are mostly important to achieve the seamless process of production and costing in advance. This study is related to the calculation of welding length and needed welding material quantity at the stage of design completion utilizing the customized CAD system. The calculated welding material quantity would be classified according to welding posture, assembly stage, block, bevel and welding type so as to improve the accuracy of total cost evaluation. Moreover it is possible to predict the working time for welding operation and could be used efficiently for the cost management using the results of this research.

• 산업공학
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• 제17권1호
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• pp.93-103
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• 2004

Service importance has been growing increasingly as competition element of enterprises according to going on rapid softness, information and knowledge of industrial infrastructure recently. Quality management system that implemented in manufacturing sector have been spreading rapidly to service company, but the company performing pure engineering service only in construction fields performed mainly the evaluation on the operational aspect such as degree of implementation of the established system because it is difficult to objective evaluation on the activity of the established quality management system or quality assurance system. This study would like to make on offer the improvement points based on the evaluation of service quality and the itself evaluation result through the questionnaire on the service offerers and customers using the pre-qualified SERVQUAL model in establishment of the improvement goal of the company. According to the result of this study, it is analyzed a gap and required to establish a counter-plan to correct many gaps discovered between the real offered level and the expect level of custom.

• Journal of Welding and Joining
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• 제8권3호
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• pp.60-69
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• 1990

Plasma arc cutting is a fusion cutting process in which a gas-constricted arc is employed to produce a high-temperature, high-velocity plasma jet on the workpiece. This process provides some advantages such as increased cutting velocity, excellent working accuracy and the ability to cut special materials (widely used stainless steels and Al-alloys, for example), when compared with iconventional oxyfuel gas cutting. From the view point of price and reliability of the power source, plasma arc cutting has also some distinct advantages over laser beam cutting. High-speed machines with NC or CNC systems are needed for the plasma arc or laser beam cutting process, while for oxyfuel gas cutting, low-speed machines with copying templates or optical-shape tracking sensors can be applied. The low price and high flexibility of the microprocessor arc contributing more and more the application of CNC system in the plasma arc cutting process, as in other manufacturing fields. From these points of view, a microprocessor-based plasma arc cutting system was developed by using a reference-pulse system, and its performance was tested. The interpolating routines were programmed in the assembly language for saving the memory volume and improving the compouting speed, which has an intimate relationship with the available cutting velocity.

• 한국기계가공학회지
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• 제7권2호
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• pp.60-65
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• 2008

The high-technology industries including a semi-conductor and an information communication need an ultra-precision technology from the technological points of view. Nano technology based on an ultra-precision technology is being studied to overcome the delicate technology that may occur in the semi-conductor fields. Then, the transferring equipment with high resolution and long displacement becomes an important technology. The goal of this study is to analyze the displacement magnification mechanism driven by piezoelectric actuator which has high resolution and fast response characteristics using flexure hinge with the merits of soft displacement, negligible back-lash and stick-slip, and no-lubrication. The analyses to reduce the magnification losses occurred during the magnification process are performed using ANSYS software based on FEM. The five design variables such as arm thickness, thickness of hinge, radius of hinge, length of input side at the 1st lever and magnification ratio of 1st lever are optimized to induce the maximum magnification ratio using Taguchi method.

• 한국생산제조학회지
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• 제21권5호
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• pp.761-766
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• 2012

Abrasive fluid jet polishing processes have been used for the polishing of optical surfaces with complex shapes. However, unstable and unpredictable polishing spots can be generated due to the fundamental property of an abrasive fluid jet that it begins to lose its coherence as the jet exits a nozzle. To solve such problems, MR fluid jet polishing has been suggested using a mixture of abrasives and MR fluid whose flow properties can be readily changed according to imposed magnetic field intensity. The MR fluid jet can be stabilized by imposed magnetic fields, thus it can remain collimated and coherent before it impinges upon the workpiece surface. In this study, MR fluid jet polishing characteristics of fused silica glass were investigated according to injection time and magnetic field intensity variations. Material removal rates and 3D profiles of the generated polishing spots were investigated. From the results, it can be confirmed that the developed MR fluid polishing system can be applied for stable and predictable precise polishing of optical parts.