• 한국초전도ㆍ저온공학회논문지
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• 제6권2호
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• pp.20-24
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• 2004

Bi-2223 wire, the first-generation high temperature superconducting (HTS) wire, was successfully commercialized and various electrical machinery and equipment are actively being developed in many countries. Because its critical current is too small to realize the lossless conducting part of electric power system with a HTS wire, multi-HTS paths are used to enlarge the critical current of HTS system. Though the resistance generated in HTS wire by transport current is very small, the difference of it in multi-path is the additional reason which causes the non-uniform current sharing in multi-HTS path except the well known reason, the difference of inductance between each path. In this paper, experimental research on current sharing of multi-strand and multi-stacked HTS wire was implemented. The whole critical current of multi-HTS paths is not equal to sum of critical current of each path because of non-uniform current sharing occurred in this paths. It was verified experimentally that Bi-2223 wires have different resistance generated by same transport current even if they was manufactured in same progress of work. Current sharing phenomenon was affected by difference of resistance and self and mutual inductance.

• 한국정보통신학회논문지
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• 제24권1호
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• pp.134-137
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• 2020

Recently, there are emphasized to support the maintenance and management system of vessels using acquired data from engine part equipment. But, there are limitations for data exchange and management. To solve the problem, the ISO published ISO 19847 and 19848. In this paper, we analyze the ISO 19848 requirements related to identify data channel ID for ship equipment, and propose the examples for applying encoding techniques. In addition, we suggest the proposed technique for applying of managing the failure and maintenance type of the ship's engine part facilities by examples. If this method is applied, the vessel's equipment can exchange data through the sharing of the code table, and express what response is needed or acted, including where the failure occurred.

• Journal of Power Electronics
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• 제13권4호
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• pp.679-691
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• 2013

High-power electromagnetic transmitter power supplies are an important part of deep geophysical exploration equipment. This is especially true in complex environments, where the ability to produce a highly accurate and stable output and safety through redundancy have become the key issues in the design of high-power electromagnetic transmitter power supplies. To solve these issues, a high-frequency switching power cascade based emission power supply is designed. By combining the circuit averaged model and the equivalent controlled source method, a modular mathematical model is established with the on-state loss and transformer induction loss being taken into account. A triple-loop control including an inner current loop, an outer voltage loop and a load current forward feedback, and a digitalized voltage/current sharing control method are proposed for the realization of the rapid, stable and highly accurate output of the system. By using a new algorithm referred to as GAPSO, which integrates a genetic algorithm and a particle swarm algorithm, the parameters of the controller are tuned. A multi-module cascade helps to achieve system redundancy. A simulation analysis of the open-loop system proves the accuracy of the established system and provides a better reflection of the characteristics of the power supply. A parameter tuning simulation proves the effectiveness of the GAPSO algorithm. A closed-loop simulation of the system and field geological exploration experiments demonstrate the effectiveness of the control method. This ensures both the system's excellent stability and the output's accuracy. It also ensures the accuracy of the established mathematical model as well as its ability to meet the requirements of practical field deep exploration.

• Journal of Construction Engineering and Project Management
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• 제2권4호
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• pp.11-19
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• 2012

Construction supply chain management (CSCM) has become one of the critical factors that determine the success of a construction project as it becomes increasingly complicated and mega-sized. Particularly for high-rise or mega-sized building construction, just-in-time supply chain management is required due to lack of storage space and effective logistics for construction components and materials at a construction site. Despite the fact that research and development of radio frequency identification (RFID) and wireless sensor network (WSN) technology have been performed, construction project managers still need to carry mobile devices and check material and component flow at each stage of the supply chain process. This research proposes that the equipment used in the construction supply chain process, such as movers, trailers, gates, and hoists, can become main actors in the supply chain process using RFID and WSN technologies. And the proposed equipment and process focused on a solution to the redundancy identification problem, which has been observed in operations that use RFID/WSN-based processes for construction logistics. This paper also presents issues identified through verification and validation of the research results and proposes further studies.

• 한국CDE학회논문집
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• 제14권1호
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• pp.1-9
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• 2009

ISO 15926 is an international standard for the representation of process plant lifecycle data. However, it is not easy to implement the part 2-data model and the part 4-initial reference data because of their complexity in terms of data structure and shortages of related development toolkits. To overcome this problem, ISO 15926-7(part 7) is under development. ISO 15926-7 specifies implementation methods for sharing and exchange of process plant lifecycle data, which is based on semantic web technologies such as OWL, Web Services, and SPARQL. For the application of ISO 15926-7, this paper discusses how to represent technical specifications of process plant equipment by defining user-defined reference data and object information model with an example of reactor coolant pumps located in the reactor coolant system of an APR 1400 nuclear power plant.

• 한국정보통신학회논문지
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• 제9권5호
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• pp.1012-1018
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• 2005

컴퓨터 산업이 발전하고 인터넷이 확산됨에 따라 원격 사용자들 간의 정보 교환을 단순 텍스트 데이터들 뿐만 아니라 음성이나 화상과 같은 멀티미디어 데이터들을 실시간으로 주고받을 수 있는 화상회의 시스템이 등장하였고 다양한 분야에서 활용되고 있다. 하지만 현재 개발된 대부분의 시스템들은 고가의 다자간 접속 장비를 필요로 하거나 높은 대역폭의 네트워크 자원을 필요로 하는 등의 문제점들을 가지고 있다. 이에 본 논문에서는 고가의 접속 장비를 사용하지 않고 최소한의 네트워크 자원을 이용해 소프트웨어적으로 안정적이고 고화질의 멀티미디어 정보 및 화면 공유 환경을 제공할 수 있는 화상회의 시스템을 설계 및 구현하였다.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2015년도 추계학술대회
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• pp.661-663
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• 2015

현재 사용되고 있거나 개발되고 있는 모바일 피트니스 시스템은 대부분 비만과 관련된 어플리케이션이다. 이러한 시스템들은 체중을 줄이기 위해 사용자에게 알림을 주거나, 사용자의 운동량을 체크하여 소모한 칼로리를 알려준다. 그러나 사용자들의 개인적인 특성이나 환경을 고려하지 않고 보편적으로 데이터를 제공 및 관리하기 때문에 정확도가 낮다. 본 논문에서는 모바일 피트니스 시스템들의 단점을 분석하고 이를 해결하기 위해 자신과 같은 BMI 그룹에 속한 타 사용자가 사용한 운동 기구를 사용자에게 알려주는 데이터 공유 메커니즘을 제시한다. 그리고 데이터 공유 메커니즘을 기반으로 한 모바일 피트니스 시스템의 설계를 다룬다.

• 한국CDE학회논문집
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• 제12권1호
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• pp.74-85
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• 2007

During the lifecycle of a nuclear power plant many organizations are involved in KOREA. Korea Plant Engineering Co. (KOPEC) participates in the design stage, Korea Hydraulic and Nuclear Power (KHNP) operates and manages all nuclear power plants in KOREA, Dusan Heavy Industries manufactures the main equipment, and a construction company constructs the plant. Even though each organization has a digital data management system inside and obtains a certain level of automation, data sharing among organizations is poor. KHNP gets drawing and technical specifications from KOPEC in the form of paper. It results in manual re-work of definition and there are potential errors in the process. A data warehouse based on a neutral model has been constructed in order to make an information bridge between design and O&M phases. GPM(generic product model), a data model from Hitachi, Japan is addressed and extended in this study. GPM has a similar architecture with ISO 15926 "life cycle data for process plant". The extension is oriented to nuclear power plants. This paper introduces some of implementation results: 1) 2D piping and instrument diagram (P&ID) and 3D CAD model exchanges and their visualization; 2) Interface between GPM-based data warehouse and KHNP ERP system.

• 한국군사과학기술학회지
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• 제14권1호
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• pp.30-38
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• 2011

The modern warfare needs sharing tactical situation and Command and Control(C2) capacity. Lately, developing of C2 System for Soldiers has dramatically increased according to increase of asymmetric state of hostilities like a guerilla war or a street-to-street fighting. In this paper, we explain the concepts of C2 System for Soldiers and Smart Phone. We describe the proposed system composed of HMD equipment, Smart Phone, and exclusive software. This system provides that Soldiers have C2 capacity and share the image of a visual field. It also offers efficient military power disposition and understanding tactical situation in operations.

• Journal of electromagnetic engineering and science
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• 제14권4호
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• pp.353-359
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• 2014

Recently, the use of mobile devices has increased, and mobile traffic is growing rapidly. In order to deal with such massive traffic, cognitive radio (CR) is applied to efficiently use limited-spectrum resources. However, there can be multiple communication systems trying to access the white space (unused spectrum), and inevitable interference may occur to cause mutual performance degradation. Therefore, understanding the effects of interference in CR-based systems is crucial to meaningful operations of these systems. In this paper, we consider a long-term evolution (LTE) system using additional spectra by accessing the TV white space, where low-power devices (LPDs) are licensed primary users, in addition to TV broadcasting service providers. We model such a heterogeneous system to analyze the co-existence problem and evaluate the interference effects of LPDs on LTE user equipment (UE) throughput. We then present methods to mitigate the interference effects of LPDs by 'de-selecting' some of the UEs to effectively increase the overall sector throughput of the CR-based LTE system.