• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.918-920
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• 2006

Metal sulfide powders such as MnS, $MoS_2$ and FeS are simply used to the machinery processing improvement agent and solid lubricant in powder metallurgy industrial. And then, metal sulfide powders have received relatively little attention from powder metallurgy. Recently, the portable machine is one of the important interfaces between human or human and electronic machine. With the increase of the intelligent activity, the social and industrial demands for information display device and power source are increasing. The transition metal sulfide materials (FeS, ZnS) have received considerable attention due to the large variety of its electric, optical and magnetic properties. Among the metal sulfide, $FeS_2$ is appealing superior material for applications in $Li-2^{nd}$ battery because of high capacity. ZnS is also a famous phosphor material with various luminescence properties, such as photoluminescence (PL) and electroluminescence (EL). So generally used in the fields of display, sensors and laser. Metal sulfide materials, therefore, are provided for most widely application in all industries. In recent years, material researchers have become increasingly interested in studying with synthesis of metal sulfide.

• International Journal of Naval Architecture and Ocean Engineering
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• 제13권1호
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• pp.674-690
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• 2021

This study proposes a hybrid marine power system combining dual-fuel generators, a fuel cell, and Vanadium Redox Flow Batteries (VRFB). Rigorous verification and validation of the dynamic modelling and integration of the system are conducted. A case study for the application of the hybrid propulsion system to a passenger ship is conducted to examine its time-variant behaviour. A comprehensive model of the reversible and irreversible capacity degradation of the VRFB stack unit is proposed and validated. The capacity retention of the VRFB stack is simulated by being integrated within the hybrid propulsion system. Reversible degradation of the VRFB stack is precisely predicted and rehabilitated based on the predefined operational schedule, while the irreversible portion is retained until the affected components are replaced. Consequently, the advantages of the VRFB system as an on-board ESS are demonstrated through the application of a hybrid propulsion system for liner shipping with fixed routes.

• 한국항해항만학회지
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• 제46권5호
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• pp.458-470
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• 2022

As the 4th industrial revolution progresses, the application of several cutting-edge technologies such as the Internet of Things, big data, and mixed reality (MR) in relation to autonomous ships is being considered in the maritime logistics field. The aim of this study was to apply the concept of a digital twin model based on Human Machine Interaction (HMI) including a digital twin model and the role of an operator to a ship. The role of the digital twin is divided into information provision, support, decision, and implementation. The role of the operator is divided into operation, decision-making, supervision, and standby. The system constituting the ship was investigated. The digital twin system that could be applied to the ship was also investigated. The cloud-based digital twin system architecture that could apply investigated applications was divided into ship data collection (part 1), cloud system (part 2), analysis system/ application (part 3), and MR/mobile system (part 4). A Mixed Reality device HoloLens was used as an HMI equipment to perform a simulation test of a digital twin system of an 8 m battery-based electric propulsion ship.

• 문화기술의 융합
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• 제7권4호
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• pp.759-764
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• 2021

전기자동차의 배터리를 스마트그리드의 한 요소로 사용하려는 Vehicle-to-Grid(V2G)기술을 사용하기 위해서는 전기자동차와 V2G 서비스 제공자 사이에 결재정보를 포함한 민감한 개인정보 교환을 위한 신뢰성 높은 통신망이 구성되어야한다. 블록체인은 암호화폐의 거래를 위해 고안된 플랫폼으로 중앙의 관리자나 제 3자의 도움을 받지 않고 동등한 노드들에 의해서만 운영되는 신뢰할 수 있는 분산된 데이터베이스 시스템이다. 본고에서는 블록체인의 구조와 운용방식에 대해 알아보고 V2G 시스템에서 블록체인의 활용에 대해 설명하고 분석하였다.

• 한국전자파학회논문지
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• 제20권5호
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• pp.450-459
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• 2009

RFID 기술은 각 사물에 전자 태그를 부착하고, 사물의 고유 ID를 무선으로 인식하여, 해당 정보를 수집, 저장, 가공, 추적하는 기술로 다양한 분야에 적용되고 있다. 이러한 RFID 시스템을 설계하는데 있어 리더가 태그 정보를 인지할 수 있는 인식 거리는 중요한 파라미터 중 하나이다. 본 논문에서는 UHF 대역 RFID 시스템의 장거리 인식 거리에 요구되는 태그를 설계하는 새로운 방법을 제안하였다. 제안한 방법에 따른 태그는 순방향 인식 거리를 확장하기 위해 전지 지원형 형태로 설계되었으며, 역방향 인식 거리를 확장하기 위해 역산란 변조 신호를 증폭하였다. 제작된 태그의 최소 문턱 전력은 -23 dBm, 역산란 증폭 이득은 28 dB임을 측정 결과를 통해 확인하였으며, 이는 시뮬레이션 결과와 일치한다. 본 논문에서 제안한 태그의 인식 거리는 상용 태그와 비교하여 2배 이상 향상되었다.

• 전기화학회지
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• 제3권2호
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• pp.72-75
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• 2000

For the purpose of developing the non-stoichiometric Zr-based Laves phase alloy with higher capacity and better performance for electrochemical application, extensive work has been carried out in KAIST. After careful alloy design of $ZrMn_2-based$ hydrogen storage alloys through varing their stoichiometry while susbstituting or adding some alloying elements, the $Zr-Ti-(Lh-V-Ni)_{2.2},\;Zr-Ti-(Mn-V-Cr-Ni)_{1.8\pm0.1}$ with high capacity and better performance was developed. Consequently the $Zr-Ti-(Mn-V-Ni)_{2.2}$ alloy has a high discharge capacity of 394mAh/g and shows a high rate capability equaling to that of commercialized $AB_5$ type alloys. On the other hand, in order to develop the hydrogen storage alloy with higher discharge capacity, the hypo-stoichiometric $Zr(Mn-V-Ni)_{2-\alpha}$ alloys substituted by Ti are under developing. As the result of competitive roles of Ti and $stocihiometry({\alpha})$, the discharge capacity of $Zr-Ti-(Mn-V-Cr-Ni)_{l.8\pm0.1}$ alloys is about 400mAh/g(410 mAh/g, which shows the highest level of performance in the Zr-based alloy developed. Our sequential endeavor is improving the shortcoming of Zr-based Laves phase alloy for commercialization, i.e., poor activation property and low rate capability, etc. It is therefore believed that the commercialization of Zr-based Laves phase hydrogen storage alloy for Ni-MH rechargeable battery is in near future.

• Advances in Energy Research
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• 제7권1호
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• pp.67-84
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• 2020

Given the recent surge of interest towards utilization of renewable distributed energy resources (DER), in particular in remote areas, this paper aims at designing an optimal hybrid system in order to supply loads of a village located in Esfarayen, North Khorasan, Iran. This paper illustrates the optimal design procedure of a standalone hybrid system which consists of Wind Turbine Generator (WTG), Photo Voltaic (PV), Diesel-generator, and Battery denoting as the Energy Storage System (ESS). The WTGs and PVs are considered as the main producers since the site's ambient conditions are suitable for such producers. Moreover, batteries are employed to smooth out the variable outputs of these renewable resources. To this end, whenever the available power generation is higher than the demanded amount, the excess energy will be stored in ESS to be injected into the system in the time of insufficient power generation. Since the standalone system is assumed to have no connection to the upstream network, it must be able to supply the loads without any load curtailment. In this regard, a Diesel-Generator can also be integrated to achieve zero loss of load. The optimal hybrid system design problem is a discrete optimization problem that is solved, here, by means of a recently-introduced meta-heuristic optimization algorithm known as Lightning Attachment Procedure Optimization (LAPO). The results are compared to those of some other methods and discussed in detail. The results also show that the total cost of the designed stand-alone system in 25 years is around 92M€ which is much less than the grid-connected system with the total cost of 205M€. In summary, the obtained simulation results demonstrate the effectiveness of the utilized optimization algorithm in finding the best results, and the designed hybrid system in serving the remote loads.

• 정보과학회 논문지
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• 제42권12호
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• pp.1623-1628
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• 2015

모바일 기기의 성능은 점진적으로 증가하여 멀티코어를 사용하는 고성능의 CPU를 장착한 스마트폰이 일상화 되었다. 그러나 고성능 기기가 사용하는 전력의 소모량을 배터리의 용량이 따라가지 못하므로 전력 관리를 위한 성능 제어가 필수적이 되었다. 이에 DVFS와 같은 Linux 기반의 전력 관리 방안이 연구되고 있으나, 동적으로 자원 요구량의 변화가 심하고 사용자의 입력이 불규칙적인 모바일 기기의 특성으로 인한 한계가 존재한다. 본 연구에서는 DVFS와 같은 기존 Linux 기반의 전력 관리 방안이 웹페이지 로딩에 있어 부족한 점을 보완하여 사용자 반응성을 유지하면서 전력 소모를 줄이는 방법으로 네트워크를 통해 연산에 필요한 데이터를 받을 때까지 CPU의 동작 Frequency을 제한하는 방안을 제안하였다. 또한, 어플리케이션 수준에서의 구현을 통하여 웹페이지 로딩 시의 전력 소모가 감소함을 확인하였다.

• 한국지능시스템학회논문지
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• 제20권1호
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• pp.21-29
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• 2010

일반적으로 풍력발전은 광범위한 영역에 지속적인 바람을 요구하는 대형 시스템 위주로 개발이 되어왔다. 그러나 소형 풍력발전 시스템은 유저에게 보다 친숙하고, 대형에 비해 보다 광범위한 적용이 가능하다는 점 때문에 최근 이에 대한 관심이 증가되고 있는 실정이다. 이에 본 연구에서는 배터리 충전에 효과적으로 도입될 수 있는 도시형 풍력발전을 위한 프로토타입 시스템에 대해 기술하며, 프로토타입 시스템에 효과적으로 도입될 수 있는 퍼지로직 기반의 최대 전력점 추종 알고리즘을 제안하고자 한다. 또한 제안된 기법의 유용성 확인을 위해 Matlab을 통한 시뮬레이션 및 이를 통해 얻어진 알고리즘을 실제 DSP에 적용하여 보고자 한다.

• 한국분말재료학회지
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• 제22권4호
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• pp.240-246
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• 2015

Anodic aluminum oxide (AAO) has been widely used for the development and fabrication of nano-powder with various morphologies such as particle, wire, rod, and tube. So far, many researchers have reported about shape control and fabrication of AAO films. However, they have reported on the shape control with different diameter and length of anodic aluminum oxide mainly. We present a combined mild-hard (or hard-mild) anodization to prepare shape-controlled AAO films. Two main parameters which are combination mild-hard (or hard-mild) anodization and run-time of voltage control are applied in this work. The voltages of mild and hard anodization are respectively 40 and 80 V. Anodization was conducted on the aluminum sheet in 0.3 mole oxalic acid at $4^{\circ}C$. AAO films with morphologies of varying interpore distance, branch-shaped pore, diameter-modulated pore and long funnel-shaped pore were fabricated. Those shapes will be able to apply to fabricate novel nano-materials with potential application which is especially a support to prevent volume expansion of inserted active materials, such as metal silicon or tin powder, in lithium ion battery. The silicon powder electrode using an AAO as a support shows outstanding cycle performance as 1003 mAh/g up to 200 cycles.