• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.4
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• pp.253-257
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• 2017

Nowadays, it is increasingly important to detect whether cables are live for the operator's safety if there is a sudden power failure. It is especially hard to detect the electrical field of an underground line because of shielding. This paper on detection of live-line states in cables studied the detection characteristics of the change in the magnetic field and axis as the frequency, voltage, and distance at the same load are changed using 3 axes. A search coil type was used as a magnetic field sensor with non-contact. We found that magnetic fields decrease proportionally to the square of the distance and the decrease of rated voltage with load effected to magnetic field. The magnetic field was detected by 3-axis sensors given correct proximity, but appeared as noise components beyond a distance of 2 cm.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2008.06a
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• pp.227-231
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• 2008

최근 국내에서 USN(Ubiquitous Sensor Network) 연구가 활성화 되면서 GIS 분야에서도 USN을 연동한 실시간 GIS 시스템이 구축되고 있다. GIS 분야 중 지하시설물은 그 중요성에 비해 관리 감독의 어려움에 의해 정량적 분석이 어려운 실정이다. 본 연구에서는 지하시설물을 획기적으로 정밀하게 관리 감독할 수 있는 UFSN(Underground Facility Sensor Network) 기반 지하시설물 관리시스템을 구축하기에 앞서 요구되는 지하시설물 관리데이터를 분석하였다. 또한 이 관리데이터를 구조화하는데 필요한 메타데이터를 USN 메타데이터 표준과 국토해양부 3차원 공간정보 메타데이터 표준을 조합하여 지하시설물 관리시스템에 필요한 메타데이터로 분류하였고, 분류된 메타데이터를 작성할 수 있는 지하시설물 메타데이터 편집도구를 개발하였다. 본 연구에서 제시한 UFSN 기반 지하시설물 메타데이터는 개발된 편집도구에 의해 작성되어 실제 관리시스템에 적용될 예정이며, 향후 USN 기반 GIS 시스템 개발에 크게 기여할 수 있을 것으로 기대된다.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2001.05a
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• pp.213-218
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• 2001

These days, corrosion condition of a underground objects is measured by the electric potential between the subject and ground. But this method is implemented by means of manual work with analog voltmeter, which is uneconomic and inefficient. So, We developed real-time On-Line cathodic protection monitoring system that is able to detect corrosion potential conditions of metal objects or various steel structures in the ground continuously, display them with the graphic screen, construct a database, and analyze them simultaneously. Since the data of corrosion and corrosion protection of all underground objects is processed automatically, not manually in this system, It is possible to reduce the manipulated error, and perform precise safety management, maintenance and inspection. As as result, this system can not only guarantee long-life operation, reduction of manpower and cost, but prevent large accidents in advance.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1997.04a
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• pp.79-86
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• 1997

In this study, pre-postprocessing toolbox is developed to perform elasto-plastic analyze of underground structures with transient ground water flow. This toolbox is composed of three modules. The first is the data input processor for the structural analysis. The preprocessing Is using GUI (Graphic User Interface), which is consist of dialog box, pull down, and short-cut icon, etc. The second is the structural analysis module. The analysis is based on the elasto-plastic finite element method involving additional options such as ground excavation effect, transient ground water flow, and rock bolts behavior. The last is the postprocessing module. The postprocessing is able to verify the result of the structural analysis by the graphical simulation which visualizes the element mesh, the node displacements, the element stress states, the stress contour, the ground water surface, and the rock bolt stresses. Since various options are considered separately in this toolbox, it is easy to modify the module of each processing, and to update other functional modules for the given analysis conditions.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.12
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• pp.597-600
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• 2006

When the energy of the nanoseconds high voltage pulse with hundreds picoseconds of the pulse rise time is emitted into the free space via an antenna, an ultra wide band electromagnetic wave is generated. This electromagnetic wave is expected to be used in transmitting vast amount of informations to far distance, high performance radars, post-packaging pasteurization of food, the detection of underground buried objects, searching of underground water veins or caves, the treatment of waste water or polluted gases and so forth. Additionally, this technology can be used in EMI(electromagnetic interference) evaluation of measuring instruments or printed circuit boards.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 1997.10a
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• pp.74-77
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• 1997

As underground distribution systems to be operated in downtown have more merits than overhead distribution system, underground distribution systems are being increased. But when pad-mounted transformers have troubles, reptures and fires can be occurred. We think that this makes accidents and power failures of bulidings and generates malaise and a great economic loss. In order to increase the reliability of pad-mounted transformers, we have investigated transformers and understood their failure mechani는. Therefore, we would have objectives and necessities of this study to improve quality and operating condition and install switches to be able to check and maintain transformers and optimize protection devices and increase cooling effect in pad-mounted transformers.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.52-56
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• 2001

Experiments of 2 type on insulating compounds accomplished to change PVC using in URD(Underground) power cable jacketing. one was DB(Dielectric Breakdown) test on the pure base resins and the others were WVT(Water Vapor Transmission) test on the compounds which contained C/B(Carbon Black), anti-oxidant to base resin. a kind of specimens made by pressing to resin of pellet or lump form was HDPE(High Density Polyethylene), MDPE(Medium Density Polyehylene), LDPE(Low Density Polyethylene), LLDPE(Linear Low Density Polyethylene), PVC(Polyvinyl Chloride). As a results of AC DB and WVT test, we saw that strength of Insulation was HDPE> LLDPE = MDP E> LDPE and WVT ratio was HDPE

• Proceedings of the KIEE Conference
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• summer
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• pp.394-396
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• 2004

In order to reduce the sheath circulating current, same arrangement and balanced length of cable are required for the underground cable system. But practically, changing the whole arrange of cable which is already constructed is impossible. Therefore, It is necessary to apply the restraining-unit of sheath circulating current at the cross-bonding wire of insulated joint because the impedance of restraining-unit is able to reduce sheath circulating current at a normal condition. Even at a transient state, the restraining-unit must maintain electrical and mechanical characteristics. In this paper, the features of restraining-unit developed by LG Cable as well as the electrical test results are described. It proves that the restraining-unit is applicable to the underground cable system where sheath circulating current rises.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.11a
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• pp.237-238
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• 2019

As part of the development of building technology to improve the living performance closely related with lifestyle to Realize the Housing Welfare, the standard manual for the prevention and maintenance of water leaks in the underground structures of apartment buildings consists of Part 1 and Part 2. This study further covered the maintenance plan and inspection carried out in Part 1.

• Journal of Korean Tunnelling and Underground Space Association
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• v.15 no.6
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• pp.613-623
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• 2013

As Limestone mines have been operated with various environmental, societal and managemental problems depending on their characteristics and developing methods, many great efforts have been applied to solve these problems. Installing the mining facilities underground is one of the successful efforts to keep the sustainable limestone mine development. This effort could reduce these problems. However, unfortunately it made an side effect of constructing a large underground space in mining site. Moreover, this space caused a necessity of various disaster managements for the safety of workers and facilities. This study introduces the priority list of a limestone mining process if there are disasters in underground mining site. This result is coming from the risk assessment and business impact analysis on survey data which were obtained from the miners of that particular limestone mine. According to the result, the highest risk is 'disregard of safety guidelines in crushing & classifier process'. The result also shows the highest priority business, above all things, is 'a pit linked work of in & out process'.