• Journal of electromagnetic engineering and science
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• v.16 no.3
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• pp.150-158
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• 2016

This paper reports on a study of LiNiZn-ferrite composite as a radiation absorbent material (RAM). The electromagnetic (EM) wave absorbers are composed of an EM wave absorbing material and a polymeric binder. The surface morphology, chemical composition, weight percent of the ferrite composite of the toroid sample, magnetic properties, and return loss are investigated using field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), vibrating sample magnetometer (VSM), and network analyzer. For preparing the absorbing sheet, chlorinated polyethylene (CPE) is used as a polymeric binder. The EM wave absorption properties of the prepared samples were studied at 4 - 8 GHz. We can confirm the effects of the thickness of the samples for absorption properties. An absorption bandwidth of more than a 10-dB return loss shifts toward a lower frequency range along with an increase in the thickness of the absorber.

• 한국벤처창업학회:학술대회논문집
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• 2017.04a
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• pp.34-34
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• 2017

본 연구는 현재 사회적으로 은퇴 또는 명퇴가 보편화 되는 관점에서 과거 은퇴예정자들은 은퇴 후 창업계획에 대해 내재된 기술과 노하우가 있어도 상당수 창업성과로 이어지지 못하고 있으며, 창업의지가 있어도 기술창업과 연계되지 못하고 소상공인 위주의 생계형 창업이 보편화 되어왔다. 은퇴자들의 준비되지 못한 자영업창업은 자영업자들의 상황을 갈수록 어려워지게 하고 있다. 경기침체에 따른 내수부진과 대기업의 골목상권 진출확대 등으로 영세자영업부진은 자영업자 가구의 상대적 빈곤율이 갈수록 높아지고 있는 것으로 나타났다. 특히, 노후대책이 미흡한 베이비부머들이 자영업에 나서지만 대부분이 실패를 하고 있으며, 55세 이상 자영업가구 10가구 중 3가구 이상이 빈곤층에 속해 우리 경제의 문제점으로 지적되고 있다. 이처럼, 장기간 내재된 직장, 단체에서의 사회적자본이나 지적자본을 활용하지 못하고 어쩔 수 없는 자영업 소상공인 위주의 창업은 결국 과다출혈경쟁과 차별적 사업전략 없이 또 다른 사회문제점으로 발현되어 사회적문제와 미래에 지불해야할 또 다른 문제요소로 자라잡고 있는 현실이다. 이런 측면에서 은퇴예정자의 창업은 창업자가 잘 할 수 있고 고객니즈의 문제점에서 아이디어를 얻고 해결할 수 있는 기술창업이 대안이라 할 수 있다. 이러한 문제적 접근을 좀 더 면밀히 분석하고자 현재 직장인들 가운데 은퇴예정자들을 대상으로 그들이 그동안 직장생활하면서 얻게 된 시회적자본과 지적자본이 기업가정신을 매개로하여 창업의지에 어떻게 영향을 미치는가를 분석하는데 그 목적이 있다.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2004.06a
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• pp.337-337
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• 2004

As one of researches for the P ＆ T purposes, a basic experiment on the recovery of actinide elements from the mixture with rare earth elements by means of electrorefining using a liquid cadmium cathode in the LiCl-KC1 eutectic melt was carried out. In order to examine the behaviors of electrodeposition of metal ions on a liquid electrode, recovery experiments of rare earth metals resulting from forming electrodeposits were performed by a galvanostatic electrolysis method at various current densities. A cyclic voltammetric technique was applied to determine reduction-oxidation potential of each metal element in the melt and to detect the changes of the multi component melt composition for on-line monitoring. Also, a collaboration study with RIAR was completed to test the preliminary feasibility on a recovery of actinide elements from the mixture with rare earth elements using a liquid cadmium cathode and actinide metals. Experimental results showed that the ratio of actinides to rare earths, 9: 0.5∼1 led to the rare earth content of about 5∼10 wt% in the deposit.

• Annual Conference on Human and Language Technology
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• 2003.10d
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• pp.177-183
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• 2003

기존의 정보검색시스템이 사용자의 질의에 의해 키워드가 포함된 의미 있는 문서를 제공하는 시스템이라면, 질의응답시스템은 사용자 질의에 맞는 정답을 적절한 언어처리 기법을 통해 텍스트로부터 추출하여 제공하는 시스템이다. 이러한 언어처리 기법을 이용한 질의응답 시스템에서 시스템의 성능 향상에 도움을 줄 수 있는 것이, 실세계의 지식을 저장하고 있는 지식베이스라 할 수 있다. 지식베이스가 가지고 있는 실세계의 지식을 어떻게 효율적으로 활용하느냐에 따라 질의 처리 분석과 정답 확률을 향상시킬 수 있는 것이다. 본 논문에서는 실세계의 지식을 어느 정도 체계적 의미적으로 반영하고 있는 것을 백과사전으로 판단하여, 백과사전의 '인물' 범주(category)를 중심으로 백과사전 지식베이스의 틀을 마련하고자 하였다. 또한 어휘의 계층적 구조를 중심으로 한 온톨로지를 백과사전 지식베이스와 유기적으로 연결시킴으로써 보다 의미 있는 지식베이스를 형성하는 방안을 모색하고자 하였다.

• Progress in Superconductivity and Cryogenics
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• v.5 no.1
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• pp.66-70
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• 2003

In a HTS transformer, the perpendicular component of magnetic flux density ($B_r$) applied to HTS tapes of pancake windings becomes larger than that of solenoid winding, thereby decreasing the critical current in the HTS tapes. This paper introduces several methods to reduce $B_r$ applied to the HTS tapes in the transformer with double pancake windings by changing winding arrangements and the relative permeability of flux diverters. We have conducted a winding design for a single-phase 1MVA 22.9kV/6.6kV HTS transformer. We observed a change of $B_r$ due to a variation of gap-length between the high voltage windings and the low voltage windings, reciprocal arrangement and an increase of the number of the high voltage pancake. We also observed a change of Br on the HTS tapes due to variation of the relative permeability of flux diverters placed between the high voltage winding and the low voltage winding. Finally, we have designed a 1MVA 22.9kV/6.6kV HTS transformer winding using suggested methods and calculated transformer parameters by the 3D finite element method.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.3
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• pp.72-78
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• 2016

In this study, we analyzed the accidental hydrogen embrittlement affecting the track nut on a self-propelled howitzer. Tracks are key components to maintain a high degree of confidence in the operation of the self-propelled howitzer and the safety of the crew. This study analyzed the fractured surface using SEM to review accidental damage of the wedge nut. In addition, we conducted revival tests and analyzed the results to identify the cause of the wedge nut damage from hydrogen embrittlement. We should carry out factor analysis and continuous improvement of the manufacturing process to determine the accidental breakage mechanism for future enhancement of the self-propelled howitzer. This study will be the useful reference for enhancing process designs in similar products.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.04a
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• pp.556-560
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• 2002

In this paper, we propose a remote controller for robot manipulator using local area network(LAN) and internet. To do this, we develope a server-client system as used in the network field. The client system is in any computer in remote place for the user to log-in the server and manage the remote factory. the server system is a computer which controls the manipulator and waits for a access from client. The server system consists of several control algorithms which is needed to drive the manipulator and networking system to transfer images that shows states of the work place, and to receive a Tmp data to run the manipulator The client system consists of 3D(dimension) graphic user interface for teaching and off-line task like simulation, external hardware interface which makes it easier for the user to teach. Using this server-client system, the user who is on remote place can edit the work schedule of manipulator, then run the machine after it is transferred and monitor the results of the task.

• Journal of Sensor Science and Technology
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• v.15 no.3
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• pp.153-157
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• 2006

This paper presents the method for three-dimensional micro structure with photoresist spray coating system. The system consists of a high temperature rotational chuck, ultrasonic spray nozzle module, angle control module and nozzle moving module. Spray coating system is effected by several parameters such as the solid contents, the dispensed volume, the scanning speed of the spray nozzle and the wafer of dimension. The photoresist (AZ 1512) has been coated on the three-dimensional micro structure by spray coating system and the characteristics have been evaluated.

• Journal of Korea Society of Digital Industry and Information Management
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• v.6 no.1
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• pp.13-22
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• 2010

In this paper, we propose a management system for positioning and indicating the surveyed control point using RFID and UMPC. This system is composed of digital control point, management system and application. The digital control point transmits information of the surveyed control point and the management system receives the data from the digital control points and manages the scattered digital control points. The system offers three services for managing the surveyed control point. The first service is control point monitoring service for identifying the change of location, locating the missing control point and the second service is control point search service notifying selected control point to user, and the third service is control point land management service for editing the control point information in the land. Therefore, this system makes it easy for administrators to access the control point information of the scattered surveyed control point through the country and enhances the managing efficiency.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.11
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• pp.1464-1469
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• 2000

The effects of SiCl$_4$addition on flame structures have been studied in flame hydrolysis deposition (FHD) processes using Coherent anti-Stokes Raman spectroscopy (CARS) and planar laser induced fluorescence (PLIF) to measure temperatures and OH concentrations, respectively. The results demonstrate that even a small amount of SiCl$_4$ addition can change thermal and chemical structures of H$_2$/O$_2$ diffusion flames. When SiCl$_4$ is added to a flame temperature decreases in non-reacting zone due to the increases in both specific heat and density of the gas mixture, while flame temperature increase in particle formation zone due to the heat release through hydrolysis and oxidation reactions of SiCl$_4$. It is also found that OH concentration decreases dramatically in particle formation zone where temperatures increase. This can be attributed to consumption of oxidative species and generation of HCl during silica formation.