• 한국표면공학회지
• /
• 제57권4호
• /
• pp.306-316
• /
• 2024

We conducted experiments to control the hydrophilic/hydrophobic properties by adjusting line and grid patterns on the surface of medical bone fixation plates using a femtosecond laser. Basic experiments were conducted using pure titanium and titanium alloy (6% alumina, 4% vanadium). The spacing of the line and grid patterns was adjusted, and surface properties were confirmed using contact angle measurement equipment. We demonstrated the feasibility of controlling hydrophilic/hydrophobic properties through the patterns of lines and grids. Based on the results of the basic experiments, surface treatment was applied to medical bone fixation plates currently used in clinical practice. Through laser processing, we confirmed a contact angle of approximately 9.18° for hydrophilicity and approximately 101.07° for hydrophobicity. We confirmed that easy control of hydrophilic/hydrophobic properties is achievable using laser processing technology and anticipate its application in various medical component fields.

• 한국위성정보통신학회논문지
• /
• 제7권2호
• /
• pp.1-7
• /
• 2012

최근들어, 에너지 자원과 환경보호의 중요성이 증가하면서, 친환경적인 소비패턴이 급격하게 증가하고 있다. 이에 따라 효율적인 에너지 소비기술이 여러 산업분야에서 주목받고 있다. 스마트그리드는 IT기술을 이용하여 에너지 효율을 상승시키는 기술로써, 이 중에서도 수요반응(Demand Response)기술은 스마트 그리드 안에서서 중요한 부분을 담당하는 기술이다. 본 논문은 과도한 전력 소모시대에 맞춰 효율적인 전력 소모를 위해 대두되고 있는 스마트그리드에 관한 전반적인 내용과 수요반응에 대한 개념, 그리고 이에 응용되는 수요반응 기술들과 그 예에 대하여 제시하고자 한다.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제16권1호
• /
• pp.97-115
• /
• 2022

Smart power grid is a user friendly system that transforms the traditional electric grid to the one that operates in a co-operative and reliable manner. Demand Response (DR) is one of the important components of the smart grid. The DR programs enable the end user participation by which they can communicate with the electricity service provider and shape their daily energy consumption patterns and reduce their consumption costs. The increasing demands of electricity owing to growing population stresses the need for optimal usage of electricity and also to look out alternative and cheap renewable sources of electricity. The solar and wind energy are the promising sources of alternative energy at present because of renewable nature and low cost implementation. The proposed work models a smart home with renewable energy units. The random nature of the renewable sources like wind and solar energy brings an uncertainty to the model developed. A stochastic dual descent optimization method is used to bring optimality to the developed model. The proposed work is validated using the simulation results. From the results it is concluded that proposed work brings a balanced usage of the grid power and the renewable energy units. The work also optimizes the daily consumption pattern thereby reducing the consumption cost for the end users of electricity.

• 전자공학회논문지A
• /
• 제29A권9호
• /
• pp.8-14
• /
• 1992

The radiation pattern of a rectangular-grid array antenna consisted of rectangular waveguides is represented by multiplication of its element and array factors. Calculated radiation patterns for excitation of TES110T mode inside the waveguides suffer from the blindness at a particular direction on E-plane. Numerical simulations show that the blindness can be removed by inserting dielectric plug inside the waveguides or covering dielectric sheath in front of the waveguides.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2008년도 하계학술대회 논문집
• /
• pp.562-564
• /
• 2008

This paper deals with the three phase high voltage power-grid connection topology using multi-level inverter. Due to the multi-level inverter, these are improved effect of fluctuating voltage, problem of EMC and switching loss using suitable switching patterns of device, above all thing, it is easy to realize the system because of using lower voltage rating switch. This topology can be applicable to power-grid connection of wind system, there is a good point about economical efficiency. The simulation results are presented to verify the validity of the proposed topology.

• 제어로봇시스템학회논문지
• /
• 제15권10호
• /
• pp.1047-1055
• /
• 2009

Since nuclear and chemical materials could damage people and disturb battlefield missions in a wide region, nuclear/chemical reconnaissance systems utilizing multiple mobile robots are highly desirable for rapid and safe reconnaissance. In this paper, we design a nuclear/chemical reconnaissance system including mobile robots. Also we propose time-efficient trajectory planning algorithms using grid coverage and contour finding methods for reconnaissance operation. For grid coverage, we performed in analysis on time consumption for various trajectory patterns generated by straight lines and arcs. We proposed BCF (Bounded Contour Finding) and BCFEP (Bounded Contour Finding with Ellipse Prediction) algorithms for contour finding. With these grid coverage and contour finding algorithms, we suggest trajectory planning algorithms for single, two or four mobile robots. Various simulations reveal that the proposed algorithms improve time-efficiency in nuclear/chemical reconnaissance missions in the given area. Also we conduct basic experiments using a commercial mobile robot and verify the time efficiency of the proposed contour finding algorithms.

• 대한조선학회논문집
• /
• 제53권4호
• /
• pp.329-335
• /
• 2016

In the present paper, Computational fluid dynamics (CFD) uncertainty analysis proposed by ITTC was investigated and applied to ship resistance performance using open source libraries, called OpenFOAM. Uncertainties for grid size, time step and iteration number were studied. Wave patterns and hull wave profile were compared for various uncertainty parameters. From results, grid size uncertainty was mainly contributed to simulation numerical uncertainty.

• 한국정보처리학회:학술대회논문집
• /
• 한국정보처리학회 2011년도 춘계학술발표대회
• /
• pp.1009-1011
• /
• 2011

With the growth of Smart Grid technologies, security and privacy will become the most important issues and more attention should be paid. There are some existing solutions about anonymization of smart meters, however, they still have some potential threats. In this paper, we describe an enhanced method to protect the privacy of consumer data. When metering data are required by a utility or the electrical energy distribution center for operational reasons, data are delivered not with the real IDs but with temporary IDs. In addition, these temporary IDs are changed randomly to prevent the attackers from analyzing the energy usage patterns. We also describe secure data transmission method for securing data delivered. In this way, we can enhance the privacy of Smart Grid System with low overhead.

• Journal of Ecology and Environment
• /
• 제37권2호
• /
• pp.53-60
• /
• 2014

The arctic tundra is an important ecosystem in terms of the organic carbon cycle and climate change, and therefore, detailed analysis of vegetation distribution patterns is required to determine their association. We used grid-sampling method and applied geostatistics to analyze spatial variability and patterns of vegetation within a two-dimensional space, and calculated the Moran's I statistics and semivariance to assess the spatial autocorrelation of vegetation. Spatially autocorrelated vegetation consisted of moss, Eriophorum vaginatum, Betula nana, and Rubus chamaemorus. Interpolation maps and cross-correlograms revealed spatial specificity of Carex aquatilis and a strong negative spatial correlation between E. vaginatum and C. aquatilis. These results suggest differences between the species in water requirements for survival in the arctic tundra. Geostatistical methods could offer valuable information for identifying the vegetation spatial distribution.

• 한국정보통신학회논문지
• /
• 제16권8호
• /
• pp.1701-1710
• /
• 2012

최근 저탄소 녹색성장이 세계적 관심사로 등장하면서 온실가스 배출을 최소화하기 위한 핵심으로 스마트 그리드라는 개념이 출현하게 되었다. 이와 같은 스마트 그리드는 전력 서비스의 효율성, 중요성, 신뢰성, 경제성, 지속성을 향상시키기 위해 모든 공급자와 소비자의 전력 생산, 공급, 소비 등을 기존 전력망과 정보통신기술을 접목하여 제공하는 시스템이다. 스마트 그리드를 통해 사용자는 자신의 집에서 사용하는 가전기기의 개별적 사용량 및 총 사용량을 실시간으로 알아볼 수 있으며, 전력 사용량이 최고에 달할 때에는 공급자가 특정 가전기기의 사용량을 제한하는 방식 등으로 효율적인 전력 공급을 수행할 수 있게 된다. 그러나 이와 같이 수집된 사용자의 정보가 노출될 경우, 전력 소비 양상, 생활 방식, 주거형태 등이 노출되는 심각한 프라이버시 문제가 발생하게 된다. 따라서 본 논문에서는 가정에서 전송되는 정보에서 어떠한 가전기기가 얼마만큼의 전력량을 사용했는지 알 수 없도록 보호하는 프로토콜을 제안한다. 본 제안 방식을 통해 전력회사라 하더라도 사용자의 패스워드 없이 어떠한 가전기기가 전력을 사용한지 알 수 없도록 한다.