• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1997년도 춘계학술대회
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• pp.475-477
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• 1997

A new open structure of the bird-cage RF coil is proposed. By applying in-phase or out-of-phase voltage to the two terminals of the open bird-cage RF coil, desirable level of RF field uniformity has been achieved. Theoretical resonance frequencies of the RF coil has been obtained and compared with experimental ones. The quality factor of the open bird-cage RF coil has been found to be comparable to the one of the conventional RF coil.

• 조명전기설비학회논문지
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• 제26권3호
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• pp.61-68
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• 2012

This paper deals with a fault diagnosis algorithm for open faults in the switching devices of PWM inverter-fed IPMSM (Interior Permanent Magnet Synchronous Motor) drive. The proposed diagnostic algorithm is realized in the controller using the informations of three-phase currents or reference line-to-line voltages, without requiring additional equipments for fault detection. Under switch open fault conditions, the conventional dq model used to control an AC motor cannot directly be applied for the analysis of drive system, since three-phase balanced condition does not hold. To overcome this limitation, a fault model based on the line-to-line voltages is employed for the simulation studies. For comparative performance evaluation through the experiments, the entire control system is implemented using digital signal processor (DSP) TMS320F28335. Simulations and experimental results are presented to verify the validity of the proposed diagnosis algorithm.

• World Technopolis Review
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• 제4권1호
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• pp.11-22
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• 2015

Globalization, increasing technological advancements and dynamic knowledge diffusion are moving our world closer together at a unique scale and pace. At the same time, our rapidly changing society is confronted with major challenges ranging from demographic to economic ones; challenges that necessitate highly innovative solutions, forcing us to reconsider the way that we actually innovate and create shared value. As such the linear, centralized innovation models of the past need to be replaced with new approaches; approaches that are based upon an open and collaborative, global network perspective where all innovation actors strategically network and collaborate, openly distribute their ideas and co-innovate/co-create in a global context utilizing our society's full innovation potential (Innovation 4.0 - Open Innovation 2.0). These emerging innovation paradigms create "an opportunity for a new entrepreneurial renaissance which can drive a Cambrian like explosion of sustainable wealth creation" (Curley 2013). Thus, in order to materialize this entrepreneurial renaissance, it is critical not only to value but also to actively employ this new innovation paradigms so as to derive community-driven shared value that stems from global innovation networks. This paper argues that there is a gap in existing business incubation model that needs to be filled, in that the innovation and entrepreneurship community cannot afford to ignore the emerging innovation paradigms and rely upon closed incubation models but has to adopt an "open incubation" (Ziouvelou 2013). The open incubation model is based on the principles of open innovation, crowdsourcing and co-creation of shared value and enables individual users and innovation stakeholders to strategically network, find collaborators and partners, co-create ideas and prototypes, share their ideas/prototypes and utilize the wisdom of the crowd to assess the value of these project ideas/prototypes, while at the same time find connections/partners, business and technical information, knowledge on start-up related topics, online tools, online content, open data and open educational material and most importantly access to capital and crowd-funding. By introducing a new incubation phase, namely the "interest phase", open incubation bridges the gap between entrepreneurial need and action and addresses the wantpreneurial needs during the innovation conception phase. In this context one such ecosystem that aligns fully with the open incubation model and theoretical approach, is the VOICE ecosystem. VOICE is an international, community-driven innovation and entrepreneurship ecosystem based on open innovation, crowdsourcing and co-creation principles that has no physical location as opposed to traditional business incubators. VOICE aims to tap into the collective intelligence of the crowd and turn their entrepreneurial interest or need into a collaborative project that will result into a prototype and to a successful "crowd-venture".

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.755-758
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• 2002

The physical phenomena of rectangular open cavity are numerically investigated in this paper Two-dimensional cavity problems with laminar boundary layers in upstream are simulated by using the compressible Wavier-Stokes equations. The high-order and high-resolution numerical schemes are used for the evaluation of spatial derivatives and the time integration. Cross-correlation is used to analyze the characteristics of wave propagation along time and spatial. Sudden phase shifting of 90 degrees is appeared near downstream edge, and this is coincident with the phase lag suggested in original Rossiter's equation. The results give a further understanding of the physical phenomenon of noise generation, and the resonance of flow and acoustic in cavity. Moreover, modified Rossiter's equation, which is more accurate and can be applied in various conditions, is suggested. The distance from the point of vortex generation to the point of vortex collapsing acts as effective distance of cavity resonance, and the phase difference between the point of vortex collapsing and the point of acoustic source acts as phase lag. The mechanism of acoustic generation is fully understood in this paper. The mechanism of acoustic generation is fully understood in this paper.

• 전자공학회논문지S
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• 제35S권5호
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• pp.42-47
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• 1998

Bridcage RF coil is one of the most widely used RF coils in MRI. In order to use birdcage RF coils in open MRI systems, an open tructured birdcage RF coil has been investigated. By opening the ring structure of an original birdcage RF coil and driving the coil at two opening ends, the original birdcage RF coil can be modified to an open structured coil. In order to improve magnetic field uniformity of the open birdcage RF coil, driving voltage phases at the two opening ends can be controlled to be in-phase or out-of-phase each other. Operating frequency of the open birdcage RF coil has been theoretically derived, and the theoretical derivation has been verified by experiments.

• 한국전자파학회논문지
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• 제25권5호
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• pp.515-525
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• 2014

본 논문에서는 저 위상잡음을 갖는 전압 제어 평판형 복합공진기 발진기(Vt-PCRO: Voltage-tuned Planar Composite Resonator Oscillator)를 설계, 제작하였다. 설계된 발진기는 공진기, 2개의 위상천이기, 증폭기로 구성된다. 공진기는 dual mode SIW(Substrate Integrated Waveguide) 공진기를 이용하여 구성하였으며, 약 40 nsec의 높은 군지연을 갖도록 하였다. 2개의 위상천이기 중(PS1, PS2: Phase Shifter 1 및 Phase Shifter 2) PS1은 $360^{\circ}$의 위상천이량을 가지며, 제작된 발진기의 전송선로 길이에 관계없이 개루프 이득(open loop gain) 발진조건을 만족하도록 한다. PS2는 약 $70^{\circ}$의 위상천이량을 가지며 발진 주파수 조정용으로 사용된다. 증폭기는 제작 시 발생한 큰 삽입손실의 문제를 보완하기 위해 2단으로 구성하였다. 개루프 이득 측정을 통해 발진 조건을 만족하는 PS1의 전압을 측정한 뒤, 폐루프로 구성하여 발진기를 구현하였다. 발진기 측정 결과, 5.345 GHz의 발진 주파수에서, 위상 잡음은 100 kHz offset 주파수에서 -130.5 dBc/Hz를 얻었다. 이때 출력 전력은 약 3.5 dBm, 전기적 주파수 조정 범위는 0~10 V의 조정 전압에서 약 4.2 MHz를 보였다.

• 폴리머
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• 제32권2호
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• pp.183-188
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• 2008

무기 점도증진제를 도입한 고내상 에멀션 중합법에 의해 고강도의 열린 기공을 갖는 미세구조 발포체를 제조하였다. 오일상 점도증진제로 유기화 점토를 사용하였고 수용상 점도증진제로는 무처리된 친수성 점토인 천연 몬모릴로나이트를 사용하였다. 고내상 에멀션의 유변물성은 오일상 점도증진제의 농도와 교반속도가 증가할수록 증가하였는데 이는 연속상 점도와 분산상 점도간의 경쟁과 전단력의 증가를 반영하여 액적의 크기를 감소시켰기 때문이었다. 점도증진제 농도에 따른 액적의 크기 변화는 캐필러리 수와 점도비 사이의 무차원 해석으로 설명할 수 있었다. 고내상 에멀션을 중합하여 제조한 발포체를 대상으로 파괴 강도 및 압축 탄성률로 표현되는 압축 물성을 측정하여 비교하였다. 본 연구에서 제조한 미세기공 발포체 중에서 반응성 작용기를 지닌 유기화 점토를 도입한 발포체의 경우 우수한 압축 물성을 보여 주었다. 이는 유기화 점토가 폴리스티렌 매트릭스 내에 박리된 형태로 존재하여 나노복합 발포체를 이루기 때문으로 사료된다.

• 디지털콘텐츠학회 논문지
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• 제18권7호
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• pp.1341-1346
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• 2017

본 논문에서는 개개인의 복합적 속성과 요구를 반영한 통합된 개인 맞춤형 서비스와 지능정보기술을 기반으로 의료서비스 접근성을 향상시킬 수 있는 개방형 서비스플랫폼의 구축방안에 대하여 설계하였다. 먼저, 데이터 수집 및 저장단계는 데이터 추출, 변환, 로딩을 반복하며 신속하고 정확하게 처리한다. ETL 모듈로부터 생성된 데이터는 분산 파일 시스템에 저장한다. 데이터 분석단계는 스토리지에 저장된 과거 의료 데이터들을 기반으로 기계학습과 데이터 마이닝 분야에서 사용되고 있는 분석 알고리즘을 적용하여 다양한 패턴들을 생성한다. 데이터 처리단계에서는 데이터를 신속히 처리해야 하므로 보통 작업을 병렬 및 분산 처리하여 성능을 향상시킨다. 데이터 제공방식은 디바이스별 운영하는 플랫폼에 독립적으로 동작해야 하며, 데이터 전송 시 네트워크 부하가 적고, 다양한 형태의 서비스를 제공하기 위하여 Open API 형태로 제공한다.

• 한국광학회:학술대회논문집
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• 한국광학회 2004년도 제15회 정기총회 및 동계학술발표회
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• pp.296-297
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• 2004

A Signal processor for the open-loop fiber optic gyroscope(FOG) is equipped with a stabilizer to reduce the error due to drift of fiber phase modulator (FPM). The stabilizer is designed to be operated to maintain the ratio of amplitude and phase between harmonics in the FOG signal. When FPM stabilizer is used, the temperature drift of FOG is reduced to less than 0.5 deg/hr in change of 20$^{\circ}C$.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 A
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• pp.135-137
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• 1994

In this paper, step response, speed, maximum frequency characteristics of 2-phase, 8-pole, HB type, prototype linear pulse motor(LPM) were investigated with the open loop control system(OLCS) being attached to the LPH. In this experiment, both 1-phase and 1-2 phase excitation types were adopted and microcomputer was used in deal with the data. The results point to some directions for the improvement of the open loop control system.