• ETRI Journal
• /
• 제35권4호
• /
• pp.638-643
• /
• 2013

This paper presents a 5-bit digital step attenuator (DSA) using a commercial 0.18-${\mu}m$ silicon-on-insulator (SOI) process for the wideband phased array antenna. Both low insertion loss and low root mean square (RMS) phase error and amplitude error are achieved employing two attenuation topologies of the switched path attenuator and the switched T-type attenuator. The attenuation coverage of 31 dB with a least significant bit of 1 dB is achieved at DC to 20 GHz. The RMS phase error and amplitude error are less than $2.5^{\circ}$ and less than 0.5 dB, respectively. The measured insertion loss of the reference state is less than 5.5 dB at 10 GHz. The input return loss and output return loss are each less than 12 dB at DC to 20 GHz. The current consumption is nearly zero with a voltage supply of 1.8 V. The chip size is $0.93mm{\times}0.68mm$, including pads. To the best of the authors' knowledge, this is the first demonstration of a low phase error DC-to-20-GHz SOI DSA.

• 한국가족관계학회지
• /
• 제22권3호
• /
• pp.73-101
• /
• 2017

Objectives: This study is to understand the experiences of overcoming pain of loss of family survivors in Suicide Bereavement Support Group(SBSG). Method: Experiential data was collected by in-depth interview(FGI, individual) to 10 family survivors(over 19) who having an experience participating in SBSG over 5months and analyzed using qualitative methodology. Results: We drew the result that 'SPACE model' which structuralize by 5 stages of suicide survivors' experience of SBSG of time path. SPACE model configured as follow: Stage1, Space in vacuum, the time to feel a sense of overwhelming feeling like pain, fear, alienation after loss of suicide, Stage2, Probing, when to find informations and resources to help survivors themselves, Stage3, Acclimation, having experiences empathy and healing as in SBSG, Stage4, Composure, accepting SBSG meaning as a part of their lives, loss of my family by suicide, and the beginning of bereavement, Stage5, Endurance, overcoming suffering through SBSG and try to help other survivors. Conclusions: SBSG is the opportunity for family survivors to overcome the pains from loss of suicide, shock, anger, grief, etc., and to empower them to help other suicide survivors.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2012년도 춘계학술대회 논문집
• /
• pp.667-671
• /
• 2012

Low frequency noises (up to about 200 Hz) mainly occur due to particular modes, resulting in booming noises, and in general the solutions may be found based on mode controls where conventional methods such as FEM can be used. However, at higher frequencies between 0.3~ 1 kHz, as the number of modes rapidly increase, radiation characteristics from structures, performances of damping sheets and sound packages may be more crucial rather than particular modes, and consequently the conventional FEM may be less practical in dealing with this kinds of structure-borne problems. In this context, so-called 'mid-frequency simulation model' based on FE-SEA hybrid method is studied and validated. Energy Transmission loss (i.e. air borne noise) is also studied. A dash panel component is chosen for this study, which is an important path that transfers both structure-borne and air borne energies into the cavity. Design modifications including structural modifications, attachment of damping sheets and application of different sound packages are taken into account and the corresponding noise characteristics are experimentally identified. It is found that the dash member behaves as a noise path. The damping sheet or sound packages have similar influences on both sound radiation and transmission loss. The comparison between experiments and simulations shows that this model could be used to predict the tendency of noise improvement.

• 한국소음진동공학회논문집
• /
• 제22권11호
• /
• pp.1071-1077
• /
• 2012

Low frequency noises(up to about 200 Hz) such as booming are mainly caused by particular modes, and in general the solutions may be found based on mode controls where conventional methods such as FEM can be used. However, at higher frequencies between 0.3~1 kHz, as the number of modes rapidly increases, radiation characteristics from structures, performances of damping sheets and sound packages may be more crucial rather than particular modes, and consequently the conventional FEM may be less practical in dealing with this kinds of structure-borne problems. In this context, so-called 'mid-frequency simulation model' based on FE-SEA hybrid method is studied and validated to reduce noise in this frequency region. Energy transmission loss(i.e. air borne noise) is also studied. A dash panel component is chosen for this study, which is an important path that transmits both structure-borne and air borne energies into the cavity. Design modifications including structural modifications, attachment of damping sheets and application of different sound packages are taken into account and the corresponding noise characteristics are experimentally identified. It is found that the dash member behaves as a noise path. The damping sheet and sound packages have similar influences on both sound radiation and transmission loss. The comparison between experiments and simulations shows that this model could be used to predict the tendency of noise improvement.

• 전자공학회논문지 IE
• /
• 제44권1호
• /
• pp.27-32
• /
• 2007

본 논문에서는 차량 이용이 많은 도심지역 편도 2차선의 도로 상에서 차량과 차량 사이에 통신이 이루어지는 경우 송.수신 차량 좌, 우측 반사체와 인접한 차량들에 의해 발생하는 다중경로파의 영향을 고려한 전파예측모델을 제안하였다. 이 때 곡선 도로의 반경을 600[m], 곡선도로의 거리는 $5.24\sim471.2[m]$, 도로교각은 $5o\sim45o$, 곡선도로에 위치한 수신차량은 도로교각과 곡선도로의 거리변화에 대응하여 최소 3.3[m]에서 최대 29.5[m]간격으로 변화시키면서 시뮬레이션 하였다. 그 결과 도로교각이 $5o\sim15o$인 경우 전파경로손실의 경우 수신 차량의 곡선도로 위치에 관계없이 1[dB]이내였고, $15o\sim45o$인 경우 도로교각이 변화함에 따라 대략 $1\sim8[dB]$이었다. 그리고 전파경로의 경우에는 도로교각의 변화에 따라 $0.4\sim120[m]$까지 변화함을 알 수 있었다. 이 때 전파경로 차가 120[m] 발생함에 따른 전파지연시간은 400[nsec]이다.

• International journal of advanced smart convergence
• /
• 제6권1호
• /
• pp.82-88
• /
• 2017

Emergency lights and exit signs are an indispensable part of safety precautions for effective evacuation in case of emergency in public buildings. These emergency sign indicates safe escape routes and emergency doors, using an internationally recognizable sign. However visibility of those signs drops drastically in case of emergency situations like fire smoke, etc. and loss of visibility causes serious problems for safety evacuation. This paper propose a novel emergency light and exit sign built-in with Bluetooth Low Energy (BLE) Beacon to assist the emergency self-guiding evacuation using devices for crisis and emergency management to avoid panic condition inside the buildings. In this approach, the emergency light and exit sign with the BLE beacons deployed in the indoor environments and the smart devices detect their indoor positions, direction to move, and next exit sign position from beacon messages and interact with map server in the Internet / Intranet over the available LTE and/or Wi-Fi network connectivity. The map server generate an optimal emergency exit path according to the nearest emergency exit based on a novel graph generation method for less route computation for each smart device. All emergency exit path data interfaces among three system components, the emergency exit signs, map server, and smart devices, have been defined for modular implementation of our emergency evacuation system. The proposed exit sign experimental system has been deployed and evaluated in real-time building environment thoroughly and gives a good evidence that the modular design of the proposed exit sign system and a novel approach to compute emergency exit path route based on the BLE beacon message, map server, and smart devices is competitive and viable.

• 한국인터넷방송통신학회논문지
• /
• 제13권6호
• /
• pp.203-210
• /
• 2013

무선 애드혹 네트워크에서는 제한된 대역폭, 간섭, 높은 패킷 에러율로 인하여 영상과 같은 고속 데이터 전송 시 높은 전송 품질을 제공하기 어렵다. 본 논문에서는 이러한 제약을 극복하고 고품질의 고속 멀티미디어 데이터 전송을 제공하기 위하여 패킷전송성공률 기반의 종단간 경로 품질과 각 중계노드에서의 잔여 대역폭 예측을 이용하는 PBBR (Path-Quality and Bandwidth-Estimation Based Routing) 프로토콜을 제안한다. 제안된 프로토콜의 성능을 검증하기 위하여 NS2를 이용한 시뮬레이션이 수행되었으며, 시뮬레이션 결과는 제안되는 프로토콜이 기존의 라우팅 프로토콜에 비해 높은 Throughput을 획득할 수 있음을 보인다.

• 대한토목학회논문집
• /
• 제28권2D호
• /
• pp.147-154
• /
• 2008

도심 내의 보행공간은 도시민의 다양한 활동이 이루어지는 공간이다. 상업가로는 그 중에서도 도시 활동이 가장 활발한 장소이지만 이용자가 원하는 물건을 찾기 위해서는 많은 시간과 비용을 지출하여야 하며 이는 도심의 경제적 활성화를 저해하는 요소로서 작용될 수 있다. 이에 상업가로를 이용하는 보행자에게 실시간으로 의미있는 경로를 제공하고 보행 이동을 보조할 수 있는 방법을 개발하고자 하였다. 우선 기존의 네트워크 표현기법을 고찰하였고 물리환경적 측면, 방향전환에 따른 보행자의 공간에 대한 인지도, 시야와 접근성의 제약에 의한 인지도 3가지 관점으로 보행자의 공간 인지를 구분하여 네트워크에 반영하고자 노력하였고 이를 시뮬레이션 하였다. 그 결과 다양한 인지요소들을 반영한 경로탐색이 가능하였으며 적절한 경로를 산출할 수 있는 방법을 제시하였다.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2008년도 제39회 하계학술대회
• /
• pp.820-821
• /
• 2008

본 논문은 FEA 기법을 이용하여 40kW급 HEV용 Traction 모터의 설계 및 고효율화를 위한 회전자 영구자석의 Eddy Current loss 저감 방안에 대한 연구를 수행하였다. 먼저 FEA 기법을 이용하여 40kW급 HEV용 Traction 모터 설계 및 특성해석을 수행하여 FEA 해석기법의 타당성을 확보하였다. 또한 Traction 모터의 손실 저감을 위해 magnet부분의 eddy current loss 저감방안에 대해 논하였으며, FEA 기법을 이용하여 회전자 magnet이 Solid, 1/2, 1/4, 1/14 segments로 나눈 타입에 따른 결과를 비교 분석하였다. 그 결과 magnet형태를 기존의 Solid 타입에서 14segments 타입으로 분할 시, magnet 내부의 current path가 줄어들어 eddy current loss가 가장 많이 저감됨을 알 수 있었으며, 이를 통해 HEV용 traction 모터의 고효율, 고성능화 설계방안을 도출 할 수 있었다.

• ETRI Journal
• /
• 제31권5호
• /
• pp.534-544
• /
• 2009

Finding link-disjoint or node-disjoint paths under multiple constraints is an effective way to improve network QoS ability, reliability, and so on. However, existing algorithms for such scheme cannot ensure a feasible solution for arbitrary networks. We propose design principles of an algorithm to fill this gap, which we arrive at by analyzing the properties of optimal solutions for the multi-constrained link-disjoint path pair problem. Based on this, we propose the link-disjoint optimal multi-constrained paths algorithm (LIDOMPA), to find the shortest link-disjoint path pair for any network. Three concepts, namely, the candidate optimal solution, the contractive constraint vector, and structure-aware non-dominance, are introduced to reduce its search space without loss of exactness. Extensive simulations show that LIDOMPA outperforms existing schemes and achieves acceptable complexity. Moreover, LIDOMPA is extended to the node-disjoint optimal multi-constrained paths algorithm (NODOMPA) for the multi-constrained node-disjoint path pair problem.