• 한국정보컨버전스학회:학술대회논문집
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• 한국정보컨버전스학회 2008년도 International conference on information convergence
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• pp.47-52
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• 2008

A radio-frequency identification(RFID) tag is a small, inexpensive microchip that emits an identifier in response to a query from a nearby reader. The price of these tags promises to drop to the range of $0.05 per unit in the next several years, offering a viable and powerful replacement for barcodes. The challenge in providing security for low-cost RFID tags is that they are computationally weak devices, unable to perform even basic symmetric-key cryptographic operations. Security researchers often therefore assume that good privacy protection in RFID tags is unattainable. In this paper, we explore a notion of minimalist cryptography suitable for RFID tags. We consider the type of security obtainable in RFID devices with a small amount of rewritable memory, but very limited computing capability. Our aim is to show that standard cryptography is not necessary as a starting point for improving security of very weak RFID devices. Our contribution is threefold: 1. We propose a new formal security model for authentication and privacy in RFID tags. This model takes into account the natural computational limitations and the likely attack scenarios for RFID tags in real-world settings. It represents a useful divergence from standard cryptographic security modeling, and thus a new view of practical formalization of minimal security requirements for low-cost RFID-tag security. 2. We describe protocol that provably achieves the properties of authentication and privacy in RFID tags in our proposed model, and in a good practical sense. Our proposed protocol involves no computationally intensive cryptographic operations, and relatively little storage. 3. Of particular practical interest, we describe some reduced-functionality variants of our protocol. We show, for instance, how static pseudonyms may considerably enhance security against eavesdropping in low-cost RFID tags. Our most basic static-pseudonym proposals require virtually no increase in existing RFID tag resources.

• 한국가스학회지
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• 제25권3호
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• pp.39-45
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• 2021

사업장에서 유해가스를 처리하는 스크러버는 처리효율은 높으나 설계가 복잡하고 24시간 펌프를 가동시켜야 하므로 많은 비용이 소모될 수 있다. 따라서, 영세한 사업장에서는 스크러버를 설치하지 않거나 순환펌프의 작동을 중지한 상태로 스크러버를 운용하여 운영비를 최소화하고 있다. 이에, 본 연구에서는 소규모 사업장에서 경제적으로 활용할 수 있는 저비용 고효율 스크러버에 대한 적용방안을 연구하였다. 저비용 고효율 스크러버는 bubble column의 방식을 적용하여 유해화학물질 흡수처리 목적으로 장치를 활용하는 것으로, 이러한 스크러버의 개발을 위하여 실험을 통해 흡수성능을 검토하였으며 특정 조건에서 물리적 조건 변화에 따른 유해가스 흡수효율 변화 및 최적의 적용방안을 연구하였다. 그 결과, 저비용 고효율 스크러버로 유입되는 기체를 어느 정도 처리할 수는 있었으나 처리능력이 저하되는 문제가 발생하여 흡수액 공급을 통해 성능저하를 방지하고 순환량에 따라 일정 수준의 흡수율을 유지할 수 있는 것을 확인할 수 있었다. 이를 기반으로 최종적으로는 적정 순환시점 및 동결 방지방안을 포함한 저비용 고효율 스크러버의 현장 적용방안을 3가지 방식(type)으로 제시하였다.

• 반도체디스플레이기술학회지
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• 제11권1호
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• pp.41-47
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• 2012

In DSSC, fundamental process conditions of upper electrode were established and low cost-oriented method for TCO layer was proposed. Especially, prominent properties, that is, open-circuit voltage of 500mV or more and short-circuit current of $25mA/cm^2$ were yielded by 2-step sintering of semiconductive powder layer. High efficiency-DSSC was able to fabricate without high cost-semiconductor apparatus in common laboratory conditions.

• 대한전자공학회논문지SD
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• 제47권3호
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• pp.35-40
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• 2010

본 논문에서는 저비용, 저전력 카메라 폰 구현을 위한 하드웨어 자원 공유가 가능한 구조의 카메라 제어 프로세서를 제안한다. 제안한 카메라 제어 프로세서의 구조는 내부에 직접 접근 경로를 내장함으로써 베이스 밴드 프로세서가 카메라 제어 프로세서의 하드웨어 자원을 직접 활용할 수 있도록 하여 베이스 밴드 프로세서의 기능 확장과 성능 향상을 도모하는데 그 목적이 있다. 또한, 제안한 구조와 결합하여 블록 단위 클럭 차단 기법을 적용하여 저전력 소비를 구현한 결과를 기술하였다. 따라서 제안한 카메라 제어 프로세서는 시스템의 하드웨어 자원 효율성을 향상시켜 저전력, 저비용 카메라 폰 시스템 구현을 가능하게 한다. 제안한 카메라 제어 프로세서는 0.18um CMOS 공정을 사용하여 제작되었으며 면적은 $3.8mm\;{\times}\;3.8mm$이다.

• 한국정밀공학회지
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• 제16권2호통권95호
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• pp.60-67
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• 1999

Micro-fabrication techniques such as lithography and LIGA processes usually require large investment and are suitable for mass production. Therefore, there is a need for a new micro-fabrication technique that is flexible and more cost effective. In this paper a novel, economical and flexible method of producing micro-pattern on silicon wafer is presented. This method relies on selective removal of mask by mechanical cutting. Then micro-pattern is produced by chemical etching. V-shaped grooved of about 3 ${\mu}m$ wide and 2 ${\mu}m$ deep has been made on ${SiO_2}m$ coated silicon wafer with this method. This method may be utilized for making microstructures in MEMS application at low cost.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 1999년도 KOBA 방송기술 워크샵 KOBA Broadcasting Technology Workshop
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• pp.171-176
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• 1999

Template matching is one of the most often used techniques for machine vision applications to find a template of size M$\times$M or subimage in a scene image of size N$\times$N. Most template matching methods, however, require pixel operations between the template and the image under analysis resulting in high computational cost of O(M2N2). So in this thesis, we present a two stage template matching method. In the first stage, we use a novel low cost feature whose complexity is approaching O(N2) to select matching candidates. In the second stage, we use conventional template matching method to find out the exact matching point. We compare the result with other methods in terms of complexity, efficiency and performance. Proposed method was proved to have constant time complexity and to be quite invariant to noise.

• 소성∙가공
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• 제30권5호
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• pp.242-246
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• 2021

Aluminum alloy sheet is being applied to automobiles continuously for the purpose of reducing car body weight. However, due to low formability, there's a limit to application of products with a deep forming depth such as door inner parts. Therefore, the difficult-to-form parts are mainly segmented formed then joined together, which is also disadvantageous as it increases the cost of manufacturing. This study proposes a hybrid cold-hot stamping method for the 1-piece door inner part to reduce cost. To design the stamping process, numerical simulation method is established by using the temperature-dependent mechanical properties of AA6016. The formability according to the hybrid cold-hot stamping method is evaluated using numerical analysis. The suitability of the proposed stamping method is then verified through the stamping tryout.

• 재활복지공학회논문지
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• 제7권2호
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• pp.7-12
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• 2013

본 논문에서는 동력의지를 위한 브러쉬리스 DC 모터 구동 시스템과 DC 링크단의 전류를 이용하여 상전류를 추정하는 기법을 제안한다. 토크제어를 위해서는 전류 측정이 매우 중요하며 전류 측정 시 스위칭 노이즈를 최소화하기 위해 전류 센싱 시점은 스위칭 전압 명령에 동기화 되어야 한다. 저가의 시스템, 공간의 절약 그리고 제어의 단순화하기 위해 DC 링크단 전류를 사용한 제어를 실시하였다. 또한 환류 다이오드를 통해 흐르는 전류에서 발생하는 DC 링크단 전류와 상전류간의 오차를 줄이기 위해 Analog MUX를 이용한 상전류 추정방법을 사용하였다. 실험 결과를 통해 제안한 시스템의 유효성을 검증하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.290.1-290.1
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• 2016

Grapehen, a single atomic layer of graphite, has been in the spotlight and researched in vaious fields, because its fine mechanical, electrical properties, flexibility and transparence. Synthesis methods for large-area graphene such as chemical vaper deposition (CVD) and mechanical, chemical exfoliation have been reported. In particular, chemical exfoliation method receive attention due to low cost process. Chemical exfoliation method require reduction of graphene oxide in the process of exfoliation such as chemical reduction by strong reductant, thermal reduction on high temperature, and optical reduction via ultraviolet light exposure. Among these reduction methods, optical reduction is free from damage by strong reductant and high temperature. However, optical reduction is economically infeasible because the high cost of short-wavelength ultraviolet light sorce. In this paper, we make graphene-oxide and lanthanoid ion mixture aqueous solution which has highly optical absorbency in selective wevelength region. Sequentially, we synthesize reduced graphene oxide (RGO) using the solution and visible laser beam. Concretely, graphene oxide is made by modified hummer's method and mix with 1 ml each ultraviolet ray absorbent Gd3+ ion, Green laser absorbent Tb3+ ion, Red laser absorbent Eu3+ ion. After that, we revivify graphene oxide by laser exposure of 300 ~ 800 nm layser 1mW/cm2 +. We demonstrate reproducibility and repeatability of RGO through FT-IR, UV-VIS, Low temperature PL, SEM, XPS and electrical measurement.

• Smart Structures and Systems
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• 제4권3호
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• pp.305-318
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• 2008

The development of a digital signal processor based prototype is described in relation to continuing efforts for realizing a fully self-contained active sensor system utilizing impedance-based structural health monitoring. The impedance method utilizes a piezoelectric material bonded to the structure under observation to act as both an actuator and sensor. By monitoring the electrical impedance of the piezoelectric material, insights into the health of the structured can be inferred. The active sensing system detailed in this paper interrogates a structure utilizing a self-sensing actuator and a low cost impedance method. Here, all the data processing, storage, and analysis is performed at the sensor location. A wireless transmitter is used to communicate the current status of the structure. With this new low cost, field deployable impedance analyzer, reliance on traditional expensive, bulky, and power consuming impedance analyzers is no longer necessary. A complete power analysis of the prototype is performed to determine the validity of power harvesting being utilized for self-containment of the hardware. Experimental validation of the prototype on a representative structure is also performed and compared to traditional methods of damage detection.