• Journal of Energy Engineering
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• v.24 no.1
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• pp.17-23
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• 2015

Electrical door system is one of the most essential items for the successful commercial operation of the railway vehicles. Nowadays, reliability values of electrical door system have a tendency to be included in technical requirements for design and manufacturing of rolling stocks. Manufacturer shall meet the reliability target values of electrical door system which is proposed by railway operator in procurement contract book. Railway operator shall approve the supplier's the reliability target values based on maintenance operation data. Railway operators are in the transition stage from the framework of maintenance interval based on time to the framework of maintenance interval based on distance. In this study, failure rates of the electrical door system currently used in railway vehicles are collected from maintenance field data. Failure rates are analyzed by using Minitab. Several kinds of plan for improving reliability are also suggested. It is necessary to keep studying on reliability prediction methodology, applying it in the field and implementing on improvement of reliability through feedback as well. Further, it will be useful for determining new maintenance policies or changing maintenance intervals for existing railway vehicles.

• Journal of IKEEE
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• v.23 no.2
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• pp.350-357
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• 2019

We analyzed the system efficiency of small solar power plants with 80% of total solar power plants. The data of the solar power plant with installed capacity of 100kW was collected and the correlation of the ESS efficiency according to the capacity of the PCS and the battery of each power plant was deduced. As a result, the higher the C-rate value affecting the discharge rate of the battery, The discharge efficiency of the plasma display panel is increased.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.11a
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• pp.815-818
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• 2007

최근 유비쿼터스 시대가 도래하면서 센서 네트워크의 중요성이 대두되고 있다. 센서 네트워크란 필요한 모든 곳에 전자태그를 부착하고, 이를 통해 사물의 인식 정보를 기본으로 주변의 환경정보까지 각종 센서를 통해 실시간으로 수집하여 관리, 통제할 수 있도록 구성한 네트워크를 말한다. 이러한 센서 네트워크에서 각 노드들은 에너지, 계산 능력, 대역폭 등에 상당한 제한을 받으며, 정보가 저장된 장치를 쉽게 도난 당할 수도 있다. 특히 보안 통신을 하기 위해 키 설정 및 관리는 필수적이며 지금까지 그로 인해 여러 가지 키 분배 및 관리 방법이 제안되었다. 본 논문은 군대 등의 특정 상황과 같이 계층적 구조를 가지는 센서 네트워크에서 더욱 효율적으로 통신을 할 수 있는 키 관리 방법을 소개하고자 한다. 기존의 계층적 구조의 취약점을 분석하고, 이를 바탕으로 레벨 키를 제안하여 같은 레벨에서 다른 그룹간 통신이 가능한 효율적인 키 분배 방안을 제시한다.

• Journal of Advanced Navigation Technology
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• v.23 no.5
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• pp.473-480
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• 2019

The smart home is a technology that can monitor and control by connecting everything to a communication network in various fields such as home appliances, energy consumers, and security devices. The Smart home is developing not only automatic control but also learning situation and user's taste and providing the result accordingly. This paper proposes a model that can provide a comfortable indoor environment control service for the user's characteristics by detecting the user's behavior as well as the automatic remote control service. The whole system consists of ESP 8266 with sensor and Wi-Fi, Firebase as a real-time database, and a smartphone application. This model is divided into functions such as learning mode when the home appliance is operated, learning control through learning results, and automatic ventilation using indoor and outdoor sensor values. The study used moving averages for temperature and humidity in the control of home appliances such as air conditioners, humidifiers and air purifiers. This system can provide higher quality service by analyzing and predicting user's characteristics through various machine learning and deep learning.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.14 no.2
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• pp.168-174
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• 2021

According to the World Agricultural Productivity Report, the current annual average growth rate of agriculture is 1.63%, which is lower than 1.73% to support the world's 10 billion people, which is growing by 2050. The demand for food, feed, and bioenergy is not growing enough to continue to meet the demand, and it is predicting a future food shortage. The purpose of this study was to create a regional irrigation control model for the purpose of reducing the production cost of crops, increasing production, and improving quality, and presenting a model that can give advice to farmers who start farming in the region. The irrigation control modeling presented in this study means to represent the change of medium weight·supply liquid·drainage amount due to changes in the root zone environment according to the passage of time and climate in a graph model. For water control modeling, we collected data on the change in the amount of the root zone environment and the weight of the badge·supply amount·drainage amount from March to June in Nonsan, Buyeo, and Yesan regions in Chungnam Province through the measuring device of the Ministry of Environment in the root region. We set up the parameters for derivation and derived an irrigation control model that can confirm the change in weight·supply liquid·drainage amount over time through the parameters.

• Proceedings of the Korean Ceranic Society Conference
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• 2005.06a
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• pp.1-112
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• 2005

This report is results of a research on recent R&D trends in electroceramics, mainly focusing on the papers submitted to the organizing committee of the International Conference on Electroceramics 2005 (ICE-2005) which was held at Seoul on 12-15 June 2005. About 380 electroceramics researchers attended at the ICE-2005 from 17 countries including Korea, presenting and discussing their recent results. Therefore, we can easily understand the recent research trends in the field of electroceramics by analyses of the subject and contents of the submitted papers. In addition to the analyses of the papers submitted to the ICE-2005, we also collected some informations about domestic and international research trends to help readers understand this report easily. We analysed the R&D trends on the basis of four main categories, that is, informatics electroceramics, energy and environment ceramics, processing and characterization of electroceramics, and emerging fields of electroceramics. Each main category has several sub-categories again. The informatics ceramics category includes integrated dielectrics and ferroelectrics, oxide and nitride semiconductors, photonic and optoelectronic devices, multilayer electronic ceramics and devices, microwave dielectrics and high frequency devices, and piezoelectric and MEMS applications. The energy and environment ceramics category has four sub-categories, that is, rechargable battery, hydrogen storage, fuel cells, and advanced energy conversion concepts. In the processing and characterization category, there exist domain, strain, and epitaxial dynamics and engineering sub-category, innovative processing and synthesis sub-category, nanostructured materials and nanotechnology sub- category, single crystal growth and characterization sub-category, theory and modeling sub-category. Nanocrystalline electroceramics, electroceramics for smart sensors, and bioceramics sub-categories are included to the emerging fields category. We hope that this report give an opportunity to understand the international research trend, not only to Korean ceramics researchers but also to science and technology policy researchers.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.3C
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• pp.281-292
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• 2008

A main application of sensor networks are to monitor and to send information about a possibly hostile environment to a powerful base station connected to a wired network. To conserve power from each sensor, intermediate network nodes should aggregate results from individual sensors. However, it can make it that a single compromised sensor can render the network useless, or worse, mislead the operator into trusting a false reading. In this paper, we propose a protocol to give us a key aggregation mechanism that intermediate network nodes could aggregate data more safely. The proposed protocol is more helpful at multi-tier network architecture in secure sessions established between sensor nodes and gateways. From simulation study, we compare the amount of the energy consumption overhead, the time of key transmission and the ratio of of key process between the proposed method and LHA-SP. The simulation result of proposed protocol is low 3.5% a lord of energy consumption than LHA-SP, the time of key transmission and the ration of key process is get improved result of each 0.3% and 0.6% than LHA-SP.

• Journal of Biosystems Engineering
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• v.9 no.2
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• pp.97-113
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• 1984

날씨가 더운지방에 소규모(小規模) 목장(牧場)들이 먼거리를 두고 산재(散在)되어 있는 경우, 각목장(各牧場)에서 생산(生産)된 우유(牛乳)를 수집(收集)해서 처리공장(處理工場)까지 수송하는 데는 많은 어려움이 있다. 현대화(現代化)된 우유처리공장(牛乳處理工場)이나 저온저장시설이 충분(充分)하지 못한 아열대지방(亞熱帶地方)에 위치(位置)한 발전도상국에서는 우유(牛乳)를 장시간(長時間) 수집(收集)하여 먼거리를 수송하는 동안 많은 양(量)의 우유(牛乳)가 부패 손실(損失)되고 있다. 이 문제를 해결(解決)하기 위하여, 그곳 현지목장(現地牧場)에 강하게 쪼이는 태양열(太陽熱)을 이용(利用)하는 것은 대단히 바람직 하다. 에너지 절약이나, 우유(牛乳)의 부패손실(腐敗損失) 막기 위하여, 태양열(太陽熱)을 이용(利用)한 소규모우유처리기(小規模牛乳處理機)를 개발하여 현지목장(現地牧場)에서 직접(直接) 우유를 처리(處理)하여 인근주민에게 공급하는 것이 가장좋은 해결방법이라 판단하고, 그 실현가능성을 확인(確認)하기 위하여 실제로 태양열(太陽熱)우유처리기(處理機) 개발(開發)을 위한 그 모형(模型)의 회로구성(回路構成)을 고찰(考察)한 결과(結果) 다음과 같다. 1. 태양열(太陽熱) 우유처리기(牛乳處理機)의 모형(模型)은 다음 4개(個)의 회로(回路)로 구성(構成)되었다. 가. 우유(牛乳)순환 회로(回路) 나. 가열회로(加熱回路) 다. 예냉회로(豫冷回路) 라. 냉각회로(冷却回路) 2. 우유가열회로(牛乳加熱回路)는 태양열(太陽熱)을 이용(利用)하였으며 냉각회로(冷却回路)는 압축식 냉각기(冷却機)를 이용(利用)하였다. 3. 자동제어(自動制御)시스템을 장치(裝置)하여 태양강도변화(太陽强度變化)에 따른 우유처리량(牛乳處理量) 조절(調節)을 자동화(自動化)할 수 있도록 하였다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.4
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• pp.925-932
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• 2015

In this paper, by utilizing the iBeacon is BLE (BlueTooth Low Energy) protocol devices that are supported by over the Bluetooth 4.0, and have implemented a system to improve the accuracy in the system for measuring the position of the user. After measuring through the system according to the state of the iBeacon, the interference factors are analyzed through analysis of the collected data, and applying the extended Kalman filter for calibration. Compared with the data after applying a filter with existing data, it was confirmed an increase in accuracy. Improvement techniques for providing the less complexity to the actual implementation, is effective in improving the accuracy of vulnerable services basic iBeacon.

• Journal of Advanced Navigation Technology
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• v.16 no.4
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• pp.709-716
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• 2012

Recently, smartgrid has interested in enable to existing electrical grid to supplying stably and efficient energy management. Smartgrid environment using PLC is transmit PLC module collected electricity consumption information in each house from PLC module to server. This communication process can occurred security threats such as personal information leak of consumer, electrical grid paralysis. In this paper, we propose efficient electricity consumption information transmission protocol with ID-based key distribution method for respond to security threats.