• 지식경영연구
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• 제15권4호
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• pp.207-221
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• 2014

Due to the awareness for the importance of social capital, many researches have investigated that social capital contributes to the successful implementation of product innovation. Although most researchers tried to model the effect of social capital on product innovation as a linear relation, we consider it too simplistic and fuzzy because knowledge utilization which ultimately leads to product innovation should exist in the relationship between social capital and product innovation. Using 107 survey data, this study found there is a partial mediating effect of knowledge utilization on the link between structure aspect of social capital and product innovation (i.e., new product development and improvement in existing products). Next, this study reported knowledge utilization does act as a perfect mediating variable on the link between awareness aspect of social capital and improvement of existing products, but act as a partial mediating variable on the link between awareness aspect of social capital and new product development. Finally, this study found that knowledge utilization does not act as a mediating variable on the link between relation aspect of social capita and product innovation.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제53권6호
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• pp.380-387
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• 2004

In accordance with the computerization of railway signaling systems, the interface link between the signaling systems has been replaced by a digital communication channel. At the same time, the importance of the communication link has become increasingly significant. However, there are some questionable matters in the current state of railway signaling systems in KNR. First, different communication protocols have been applied to create an interface between railway signaling systems although the protocols have the same functions. Next, the communication protocols currently used in the railway fields have some illogical parts such as structure, byte formation, error correction scheme, and so on. To solve these matters, the standard communication protocol for railway signaling systems is designed. The newly designed protocol is overviews in this paper. And the simulation is performed to analysis the performance of data link control for designed protocol. According to this simulation, it is identified that the link throughput of new protocol is improved about 10% and the frame error rate is improved than existing protocol. And it is verified the safety and liveness properties of designed protocol by using a formal method for specifying the designed protocol. It is expected that there will be an increase in safety, reliability and efficiency in terms of the maintenance of the signaling systems by using the designed communication protocol for railway signaling.

• 전기학회논문지
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• 제63권10호
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• pp.1402-1411
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• 2014

In this paper, the Maximum Power Point Tracking(MPPT) control of the small scale wind power generation system with a three-phase diode rectifier and the grid-connected inverter is studied. Without the need for the converter circuits to control speed of the generator, it is economical and the structure is simple. Compared with existing systems, it can be to reduce the power semiconductor switches and passive elements, and to implement the MPPT control with only DC-Link voltage control of the grid-connected inverter. In order to allow MPPT control without the characteristic information of the wind turbine, the P&O algorithm is applied, and these are verified by the simulation and experiment.

• 한국광학회지
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• 제12권2호
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• pp.129-134
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• 2001

본 논문에서는 일반적인 OTDR 기술로 WDM 전송시스템의 감시를 수행하는 새로운 방법을 제안하였다. 제안된 감시 방법은 전송로에 포함된 EDFA의 구조를 광회전기(optical circulator)와 FBG(Fiber Bragg Grating)를 이용하여 OTDR 광펄스의 파장에서만 양방향 전송이 가능하도록 변경하고, 전송 신호의 역방향으로 OTDR 광펄스를 삽입함으로써 EDFA의 교차이득변조에 의한 신호왜곡을 분산시켜 신호전송과 전송로 감시를 동시에 수행하는 것이다. 이 감시 방법의 타당성을 검증하기 위해 제안된 구조로 변경된 EDFA가 포함된 320km 길이의 8 채널 WDM 광전송 시스템을 구축하고 신호전송과 동시에 전송로 감시를 수행한 결과를 보였으며, 이때 전송로 감시로 인한 전송 신호 채널의 power penalty를 BERT로 측정하여 그 값이 0.3dB이하로 매우 작음을 보였다.

• Journal of Electrical Engineering and Technology
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• 제8권3호
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• pp.638-648
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• 2013

Together with the GPS-based approach, geo-location through mobile communication networks is a key technology for location-based service. To save the cost, most geo-location system is implemented on the existed network service, which has a cellular structure. Still, multilateration is limited in cellular structure because it is difficult for the mobile terminal to acquire distance measurements from multiple base stations. This low hearability in the receiver is caused by co-channel interference and multipath environment. Therefore, hearability enhancement is necessary for multilateration under multipath and interference environment. Former time domain based hearability methods were designed for real signals. However, orthogonal frequency division multiplexing (OFDM) signal, which its usage has been increased in digital wireless communication, is a complex signal. Thus, different hearability enhancement method is needed for OFDM signals. This paper proposes a hearability enhancement method for forward-link multilateration using OFDM signals, which employ interference cancellation and multipath mitigation. A novel interference cancellation and multipath mitigation strategy for complex-valued OFDM signals is presented that has an iterative structure. Simulation results show that the proposed multilateration method provides the user's position with an accuracy of less than 80m through the mobile WiMAX cellular network in multipath environment.

• 한국정밀공학회지
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• 제22권7호
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• pp.146-154
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• 2005

Recently, the high-speed and intelligence technology of machine tools are developed for the high efficiency of productivity Under the operating condition from the high-speed of machine tools, the various failure modes can occur in core units of manufacturing system. Therefore it is for the reliability concept of machine tool to be required in a design level. And the above-stated technology must be accommodated in the feeding and spindle subsystem, etc those are the core units of machine tools. In this study, we are developed the test-bed of sliding cover (C-plate) in order to evaluating reliability and estimating failure modes of feeding subsystem under operating conditions. The reliability experiment using the developed test-bed and the additional structural analysis executed on single and double structure. We found out the weak parts of sliding cover and were able to predict a life cycle from the experiment results. In this study, we propose the new C-plate model with double link structure to apply the high-speed machine tool in the fundamental guideline.

• Steel and Composite Structures
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• 제38권4호
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• pp.381-397
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• 2021

Based on the spatial substructure hybrid simulation test (SHST) method, the seismic performance of a high-strength steel composite K-eccentrically braced frame (K-HSS-EBF) structure system is studied. First, on the basis of the existing pseudostatic experiments, a numerical model corresponding to the experimental model was established using OpenSees, which mainly simulated the shear effect of the shear links. A three-story and five-span spatial K-HSS-EBF was taken as the prototype, and SHST was performed with a half-scale SHST model. According to the test results, the validity of the SHST model was verified, and the main seismic performance indexes of the experimental substructure under different seismic waves were studied. The results show that the hybrid simulation results are basically consistent with the numerical simulation results of the global structure. The deformation of each story is mainly concentrated in the web of the shear link owing to shear deformation. The maximum interstory drifts of the model structure during Strength Level Earthquake (SLE) and Maximum Considered Earthquake (MCE) meet the demands of interstory limitations in the Chinese seismic design code of buildings. In conclusion, the seismic response characteristics of the K-HSS-EBFs are successfully simulated using the spatial SHST, which shows that the K-HSS-EBFs have good seismic performance.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2018년도 추계학술대회
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• pp.571-573
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• 2018

무선 센서 네트워크는 싱크 노드로 데이터가 집중되는 수렴적인 구조로 인해 네트워크 내 불균형적인 에너지 소모가 발생한다. 이러한 문제를 해결하기 위해 기존 연구에서는 소스 노드 및 싱크 노드 사이에 중계 노드를 배치하여 싱크 노드로 집중되기 전 데이터를 병합 및 처리하였다. 하지만 링크 품질을 고려하지 않은 중계 노드의 배치는 재구성된 라우팅 경로의 링크 품질에 따른 패킷 손실을 야기한다. 따라서 본 논문에서는 중계 노드 선정을 위한 라우팅 경로 재구성 시 데이터 신뢰성을 고려한 링크 비용 산출 방법을 제안한다. 라우팅 메트릭 값으로 홉 수 및 RSSI를 고려한 링크 비용 산출 수식을 제안하며 센서 모듈 간 패킷 전송 실험을 통해 RSSI 임계값을 선정한다.

• 한국군사과학기술학회지
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• 제13권3호
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• pp.397-404
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• 2010

Recently, there is on-going research about tactical data link system based on the legacy radio. Tactical data link based on legacy radio is operated mostly in narrow bandwidth under 25khz. Communicating traffics in nodes participated at network need to be minimized for distributing tactical data in narrow bandwidth. In addition, the data distributing structure is necessary for distributing tactical informations such as a situation awareness and so on to war fighters. However, conventional server-client system wastes a lot of time to obtain information for war fighters as user uses pull system to gather necessary information by seeking it one by one. Especially, the fighter pilot is supposed to dedicate into a situation awareness and fight mission in every seconds but seeking information of a user terminal while aircraft maneuvering affects as obstacle to concentrate engaging hostiles. therefore, push technology, the tactical data distributing system, is necessary for war fighters to receive fixed tactical data automatically without putting attention to it. This paper propose the UMPC tactical data link push framework. the UMPC tactical data link is a tactical data link system based on the legacy radio. Proposed push framework is verified by composing experiment environment and testing.

• 한국통신학회논문지
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• 제41권10호
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• pp.1210-1220
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• 2016

현대전이 네트워크 중심전으로 변화함에 따라 아군 플랫폼끼리 상황인식 정보를 공유하는 능력은 작전임무 수행을 위한 핵심 능력이 되었다. 공중 환경에서 상황인식 공유를 위하여 Link-16과 같은 전술 데이터링크를 이용하는데, 슬롯 할당이 동적으로 되지 않거나 동적으로 할당된 슬롯의 개수를 변경하지 못하는 문제가 존재하였다. 또한 슬롯할당을 받지 못한 노드가 있는 경우 상황인식 공유의 필요에도 불구하고 유한한 타임 슬롯 자원의 한계로 이를 공유하지 못하여 상황인식 능력을 향상시키지 못하는 문제가 존재하였다. 본 논문에서는 TDMA (time division multiple access)와 랜덤액세스가 혼합된 구조를 활용하여 동적인 슬롯할당 및 할당 슬롯의 변화를 수용하며, 사용 가능한 슬롯이 소진된 경우에도 일부 상황인식 공유가 가능한 기법 및 슬롯 요청이나 메시지 전송 집중에 다른 슬롯 할당 지연시간을 감소를 위한 서브프레임간 부하 분산 기법을 제안한다.