• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.2
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• pp.121-126
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• 2015

In this research, a tool was developed for the rapid performance of three-dimensional finite element analysis (3D FEA) of a machine tool spindle system made of a shaft and bearings. It runs the FEA with data, such as the bearing stiffness and the coordinates of the points, to define the section of the shaft, bearing positions, and cutting point. developed for the spindle system and then implemented with the tool using an object-oriented programing technique that allows the use of the objects of the CAD system used in this research. Graphic user interfaces were designed for a user to interact with the tool. It provides rapid evaluation of the design of a spindle system, and therefore, it would be helpful to identify a near optimal design of a spindle system based on, say, static stiffness with design changes and, consequently, FEA.

• 한국정보통신설비학회:학술대회논문집
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• 2002.08a
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• pp.85-104
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• 2002

최근 정부(정보통신부)는 사이버 아파트를 포함하여 초고속 정보통신망을 2005년까지 구축하여 각 가정당 10Mbps의 고속 정보통신서비스를 실현한다는 계획을 발표하고, 초고속 정보통신을 활성화하므로 정보통신 선진국 진입을 위하여 "초고속 정보통신 건물 인증제도"를 발표, 현재 시행하고 있다. (1999.7 제정발표) 그러나 시행 과정에서 아파트 중앙 관리실에 있는 MDF 이후의 광케이블과 기타 공사는 건설회사에서 시공하고 중앙 관리실 MDF 이전의 광케이블 공사와 중앙관리실 LAN시설 등의 공사는 통신 전문업체로 하여금, 입주자 별도 부담금으로 시공하고 있다. (컨소시엄구성) 최근 아파트 분양열기 고조로 건설회사 마다 "초고속 정보통신아파트"인증 1등급이라고 선전 및 분양광고 중인데 실제는 "1등급"이 아니고 "2등급" 또는 "3등급"인 경우가 있어, 정부가 목표하는 각 가정당 10Mbps, 개인당 2Mbps 고속정보통신 서비스는 실현성 문제점이 있다. 정부의 인증심사 기준에 중앙관리실 장비 등에 대한 것은 심사기준에 누락되어 있고 또 사생활 정보보호를 위한 대응기술, 시스템 준비 정도까지 포함하여 종합적으로 평가한 뒤 인증을 부여하여야 한다는 것이 본인의 연구 초점이다. 사이버 아파트란 광통신을 주축으로 영상과 음성, 데이터를 자유 자재로 전송 처리하는 초고속 정보통신망을 이용하는 것으로 LAN 장비를 이용하여 각 세대간 통신은 물론 누구나 인터넷을 사용할 수 있는 기능이 있는 설계된 아파트를 말한다. 사이버 아파트의 네트워크에는 금융, 홈쇼핑, 예약, 지역정보, 관공서, 의료서비스, 레저 생활정보 등 차별화된 콘텐츠 확보가 필요하다. 본 연구의 핵심은 사이버 아파트의 현 실태와 문제점, 정부의 인증심사 기준의 미비점과 문제점, 사이버 아파트의 기능, 구성요소, 시스템 구축, 서버활용도, 장비들에 관한 것과 그리고 정부의 사이버 아파트 육성정책, 정보보호 대책과 관련업체들의 동향 등을 연구하여 요약 정리하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.6
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• pp.3357-3362
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• 2014

The purpose of this research was to develop a resonance electric power generator to harvest vibration energy while the vehicle is driving on a road surface. The electric power generator in the paper was designed using the resonance phenomenon to effectively respond to vibrations from the road surface, which is a comparatively small energy source. Vibration displacement analysis using MATLAB and transient analysis using Ansys MAXWELL, which is a commercial electromagnetic analysis program, was performed to predict the input velocity for the generator and verify the electric power generation. If this electric power generator is applicable to hybrid or electric vehicles, it can be valuable around an automotive electric system and help maintain the performance of the vehicle battery.

• The Journal of Korean Association of Computer Education
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• v.11 no.5
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• pp.77-88
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• 2008

Having observed the restriction of the current Web technology, the semantic Web has been developed, and it now has grown up with the core help of the W3C to a level where it recommends the OWL Web ontology language. Besides, in order to deduce the information out of OWL data, several inference systems have been developed such as Jena, Jess, and JTP. Unfortunately, however, quite few systems can effectively handle recently developed OWL data, and further, due to the limitation of file-based operation, the current inference systems cannot meet the requirements for handing huge OWL data. An efficient method for storing and searching ontology data is essential for ensuring stable information inference processes. In this study, firstly, we proposed a model based on the database management system to transform and store OWL data and to enable deduction process from the database. Secondly, we designed and implemented an effective OWL storing system based on our model. Finally, we compare our system with the previous inference systems through experimental performance analysis.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.04a
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• pp.398-403
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• 2004

The demand of high speed machining is increasing because the high speed cutting providers high efficiency of process, short process time, improved metal removal capacity and better surface finish. Active magnetic bearings allow much high surface speed than conventional ball bearings and therefore greatly suitable for high speed cutting. The automatic control concept of magnetic bearing system provides ability of intelligent control of spindle system to increase accuracy and flexibility by means of adaptive vibration control. This paper describes a design and development of a milling spindle system which includes built-in motor with power 5.5㎾ and maximum speed 70,000rpm, HSK-32C tool holer and active magnetic bearing system. Magnetic actuators are designed for satisfying static load condition. The Performances of manufactured spindle system was examined for its static and dynamic stiffness, load capacity, and rotational accuracy. This spindle was run up to 70,000 rpm stably, which is 3.5 million DmN.

• Spatial Information Research
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• v.7 no.2
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• pp.175-190
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• 1999

Recently , as GIS technology is rapidly improved and stabilized, there are some needs to reuse pre-developed and powerful GIS technology. GIS standardization based on components and open interfaces becomes a way to solve those reusability of previous GIS technology. This GIS standardization currently focuses on building the GIS Data Infrastructure that is being deployed globally. Especially, OpenGIS consortium which is mainly made up of international GIS leading vendors is announcing some GIS abstract specifications and implementation specifications. This study focuses on how could we design and implement the OLE/COM-based data provider component based on various DBMS or file systems, how could these data provider components be used for enterprise UIS(Urban Information Systems) and how could various formatted GIS data be shared in one system. Also some problems practically caused by an implementation process of data provider component are listed up and some solutions are given. Furthermore, design and analysis of UML(Unified Modeling Language) was reformed through the data provider component development task and this UML methodology is able to indicate a standardized model for newly developed data provider component.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.12C
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• pp.249-254
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• 2001

A receiver ASIC for fiber optic modules of STM-1 optical communication has been fabricated with 0.65 $\mu\textrm{m}$ CMOS technology. The ASIC has a limit amplifier circuit for the 155.52 Mbps data reshaping, and a clock extraction circuit for the 155.52 MHz clock recovery. The ASIC has an acquisition aid and LOS monitoring circuit for properly operation with near 155.52 MHz clock frequency in case of the data loss due to transmission line open or data transfer fail. Measured results show that the circuit reshapes data from 5 mV to 1 V wide range of input voltage condition, add it recovers system clock with stable on any condition.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.2
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• pp.141-146
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• 2016

This paper presents a method to improve time interval error for asynchronous communication systems. The proposed method is designed and simulated with multi-phase VCO, interpolator, phase selector, up-down counter, comparator and adder. The simulation results for CAN communication system show that the maximum time interval error can be tightly managed for satisfying the required specification. The proposed frequency modulation method can be properly used for asynchronous communication systems requiring high reliability.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2019.05a
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• pp.564-565
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• 2019

The Internet of Things technology is regarded as the next major technology that will be the driving force behind the fourth industrial revolution. The characteristics of entities for Internet of Things application are changing more actively and actively, requiring a more detailed approach, but existing access control technologies are designed around users, requiring access control techniques that maintain efficiency and security with less system load to apply complex and variable content. Therefore, research on role-based access controls that are appropriate for Internet of Things entities is essential. In this study, the relevant research for the study of access control of the Internet of Things entities and the RBAC and AC methods that can define the properties of the various entities within the Internet of Things.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.4
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• pp.2338-2343
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• 2015

An analytical model was developed in this study and then implemented into a tool for automation of FEA (Finite Element Analysis) of a spindle system for natural frequencies and modes in the universal FEA software, ANSYS. VBA of EXCEL was used for the implementation. It allowed graphic user interfaces (GUIs) to be developed for a user to interact with the tool and, in addition, an EXCEL spreadsheet to be used for data arrangement. A code was developed in the language of ANSYS to generate the geometric model of the spindle system, sequentially to construct the analytical model based on the information in the GUIs, and finally to perform computation for the FEA. Its automation of the model generation and analysis can help to identify a near optimal design of the spindle system under design in minimum time and efforts.