• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.8 no.4
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• pp.38-45
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• 1994

It is very imprtant and necessary to predict luminous enviroment in an interior space. This paper has de scribed about energy saving and evaluated interior visual environment in a office building having on/off turning control lighting system utilizing daylight. In order to predict the interior varior illumination distribution, the scale model w a m~a de and examined under various conditions, such ad difference of window glass, and color pattern of wall, floor, and also ceiling lighting system type. Ths paper suggests that basic fundamental data of lighting design ~rformancein the concept and schematic stages of design.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.10a
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• pp.130-136
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• 2009

The goal of this paper is to develop a standard side mirror geometry that will perform well across multiple vehicles. One of the important performance attributes of a side mirror is the amount of wind noise generated under the flow conditions on a car. PowerFLOW can be used for Computer Aided Testing of the aeroacoustics performance of a design in addition to directing design modifications based on a detailed analysis of the flow structures responsible for the noise generation. Alternatively, a Design of Experiment (DOE) approach is useful to explore the design space without any a-priori assumptions of the effects of design parameter changes. Some general design guidelines regarding the significant mirror geometry factors will be determined which may help to reduce vehicle development time and cost in the future. The results of this research will also allow us to estimate the trade-off between cost saving and performance optimum related to using a standard mirror shape for different vehicles.

• Proceedings of the Korean Information Science Society Conference
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• 2005.11a
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• pp.175-177
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• 2005

무선 센서 네트워크에서는 배터리에 의존하는 수많은 센서 노드들로 구성이 된다. 이때, 물체들을 감지하기 위해서는 센서들은 켜져 있어야 하고, 수집한 데이터는 클러스터 헤드(Cluster Head)나 싱크(sink) 로 보내주어야 한다. 일련의 동작을 위해서 센서들은 않은 에너지를 소모하게 된다 이를 보완하기 위해서 LEACH 라는 방법을 이용하여, 클러스터 헤드 만이 싱크로 데이터를 전송하고, 에너지를 균일하게 소모하기 위한 기법을 사용한다. 본 논문에서는 기본적으로 LEACH 방법을 이용하면서, 이동체의 이동을 감지함에 있어서, 이동체의 예상 이동영역을 예측하여, 예상 이동영역내에 존재하지 않는 센서 노드들은 다음 라운드가 시작할 때까지 Sleep 하도록 하고. 예상 이동영역내에 있는 센서 노드들만 감지하도록 하여, 에너지의 소모를 줄였다. 이때 예상 이동영역은 싱크가 이전에 수집한 데이터로 계산하여, 이동체들의 정보를 모든 노드들에게 브로드 캐스트(Broadcast)하고, 매 라운드마다 클러스터 헤드선택까지는 LEACH 와 마찬가지로 모든 센서 노드들이 참여하지만, 이후 클러스터의 구성원이 되기 위해서는 예상 이동영역내에 존재해야 한다. 만약 해당 라운드에서클러스터 헤드가 되어도, 구성원이 존재하지 않는 다면 다시 Sleep 하도록 하여, 에너지 소모를 줄였다.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.3
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• pp.453-458
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• 2013

Aside from the issues like energy saving and maximizing network lifetime. WMSN has another issue to deal with: support of quality of service(QoS) which is required especially for handling real-time data such as object tracking and data gathering. This paper proposes a multipath routing algorithm considering the distance to sink node, energy level and link quality of neighbour nodes. Proposed algorithm supports multipath routing path with high quality links. Hence it helps to reduce a power consumption concentration that happens in particular set of nodes along the frequently selected route. It also specifies a service quality pattern and a service quality level depending on traffic pattern. By doing this, the proposed algorithm can realize a differentiated service with QoS guaranteed data transmission.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.7 no.2
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• pp.35-40
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• 2013

In WBAN environment, it is very important to achieve energy efficiency of master and nodes, At the same time, a master also plays an important role in collecting data from nodes and controlling the nodes. By maintaining a master properly, any kinds of situation can be handled. Therefore, low power MAC protocol between a master and a node is highly required appropriately. We propose an improved MAC protocol by simply changing the frame structure of WBAN system. The simulation results show that the proposed scheme attains a lot of saving of energy consumption of master and each node compared with IEEE 802.15.6 and conventional schemes.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.3
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• pp.47-55
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• 2008

본 논문에서는 모바일 ad-hoc 무선 센서 네트워크[1]에서 안정된 경로의 설정 및 설정된 경로의 lifetime 을 효과적으로 지원하여 데이터 전송효율을 향상시키기 위한 협력 도움 라우팅 프로토콜(CARP: Cooperative_Aided Routing Protocol) 을 제안한다. 제안된 라우팅 프로토콜의 기본 아이디어 및 특징은 다음과 같다. 첫째, 소스노드와 목적지 노드 사이의 안정된 라우팅 경로의 설정이다. 본 연구에서는 모바일 노드들의 이동성 정보를 이용한 엔트로피 기반의 안정된 경로 설정방법을 제안 사용한다. 둘째, 협력도움 전송 방법이다[3][4][5]. 설정된 경로 위로 데이터 패킷을 전송 할 때 경로 lifetime과 SNR의 효과적인 지원으로 데이터 전송률을 증가시키기 위해 이웃 노드들로부터 협력 도움을 받는다. 셋째, 기존의 센서 네트워크는 주로 고정된 노드 환경에서 많은 연구가 되어 왔지만, 본 연구에서는 노드들의 이동성을 고려한 환경에서 연구가 이루어진다. 제안된 CARP 의 성능평가는 OPNET(Optimized Network Engineering Tool)을 사용하여 이루어졌으며 성능평가를 통하여 제안한 프로토콜은 안정된 경로의 설정 및 데이터 전송효율을 효과적으로 증가 시킬 수 있음을 알 수 있다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.11
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• pp.1550-1559
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• 2013

Light emitting diode(LED) lighting has been applied various industry fields because of its high efficiency, low power consumption, long life time, and environment friendly characteristics. Generally, LED lighting needs a driver to maintain constant current. Most popular driver is the switching converter. In the converter, there are several electrolytic capacitors. However the lifespan of the electrolytic capacitor is much shorter than LED. Therefore the lifespan of LED lighting with electrolytic capacitor is decreased. Also, LED lighting needs dimming control because of various needs and energy saving. This paper presents the dimmable single-stage PFC DCM flyback converter without electrolytic capacitor and parallel LC resonant filter for reducing 120[Hz] ripple on the output. The type 2 controller is used to maintain constant current and the analog dimming control is used. The proposed converter is verified through simulation and experimental works.

• Journal of the Korean Institute of Gas
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• v.17 no.6
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• pp.20-26
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• 2013

In this study, based on a 12L class diesel engine, a natural gas-diesel dual fuel engine was developed by adding natural gas fuel supply system. For optimal control of dual fuel engine, a conventional diesel engine ECU and a dual fuel ECU were utilized. To convert the dual fuel engine, MPI natural gas injectors were installed on the new modified intake manifold adapter. As a results, the dual fuel engine showed same level of torque, power performance and exhaust gas emissions as those of a diesel base engine.. Furthermore, overall fuel replacement rate was 70~76 % and total fuel cost saving was 37~40%.

• Journal of Electrical Engineering and Technology
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• v.11 no.6
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• pp.1645-1655
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• 2016

A Dynamic Voltage Restorer (DVR) model is proposed to eliminate the short-term voltage disturbances that occur in the grid-connected mode, the switching between grid-connected mode and the stand-alone mode of a Microgrid. The proposed DVR structure is based on a conventional cascaded H-bridge multilevel inverter (MLI) topology; a novel composite control strategy is presented, which could ensure the compensation ability of voltage sag by the DVR. Moreover, the compensation to specified order of harmonic is added to implement effects that zero-steady error compensation to harmonic voltage in specified order of the presented control strategy; utilizing wind turbines-batteries units as DC energy storage components in the Microgrid, the operation cost of the DVR is reduced. When the Microgrid operates under stand-alone mode, the DVR can operate on microsource mode, which could ease the power supply from the main grid (distribution network) and consequently be favorable for energy saving and emission reduction. Simulation results validate the robustness and effective of the proposed DVR system.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.3
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• pp.1246-1259
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• 2015

Certificate-based signature (CBS) combines the advantages of both public key-based signature and identity-based signature, while saving from the disadvantages of drawbacks in both PKS and IBS. The insecure deployment of CBS under the hostile circumstances usually causes the exposure of signing key to be inescapable. To resist the threat of key leakage, we present a pairing-free key insulated CBS scheme by incorporating the idea of key insulated mechanism and CBS. Our scheme eliminates the costly pairing operations and as a matter of fact outperforms the existing key insulated CBS schemes. It is more suitable for low-power devices. Furthermore, the unforgeability of our scheme has been formally proven to rest on the discrete logarithm assumption in the random oracle model.