• Journal of Power Electronics
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• 제19권4호
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• pp.869-880
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• 2019

Due to the inherent feedforward of load current, capacitor current (CC) control shows a fast transient response that makes it suitable for the power supplies used in various portable electronic devices. However, considering the effect of the outer voltage loop, the stable range of the duty-cycle is significantly diminished in CC controlled buck converters. To investigate the stability effect of the outer voltage loop on buck converters, a CC controlled buck converter with a proportion-integral (PI) compensator is taken as an example, and its second-order discrete-time model is established. Based on this model, the instability caused by the duty-cycle is discussed with consideration of the outer voltage loop. Then the dynamical effects of the feedback gain of the PI compensator and the equivalent series resistance (ESR) of the output capacitor on the CC controlled buck converter with a PI compensator are studied. Furthermore, the design-oriented closed-loop stability criterion is derived. Finally, PSIM simulations and experimental results are supplied to verify the theoretical analyses.

• 대한전자공학회논문지SP
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• 제48권3호
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• pp.79-89
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• 2011

임베디드 프로세서의 발달로 인해 휴대 단말을 이용한 동영상의 실시간 재생이 가능하게 되었으나, 휴대 단말의 제한된 배터리와 낮은 프로세서의 연산 능력을 고려할 때 고화질 및 고해상도 동영상의 실시간 복호화 구현에는 아직 어려움이 있다. 이러한 문제점을 해결하기 위하여 기존에 연구되었던 복호화 요소들의 연산 복잡도를 조절하여 비디오 복호화기의 복잡도를 조절하는 방법들을 사용할 수는 있으나 부/복호화기 사이의 연산 과정의 불일치에 의한 에러 전파로 객관적 화질이 크게 떨어 지는 문제점이 발생한다. 본 논문에서는 저 복잡도 비디오 복호화기를 달성하기 위해 B 슬라이스의 선택적인 복호화 스킵 방법을 제안한다. 제안 방법은 B 슬라이스를 복호화 하기에 앞서 특정 조건을 만족하는지 여부를 판단하여 해당 B 슬라이스의 선택적 복호화 스킵을 결정하고, 복호화 스킵일 경우 주변 복호화 된 참조 화면들을 사용하여 해당 B 슬라이스를 매우 간략한 방법으로 복원한다. 실험 결과를 통해 제안 방법은 복호화기의 복잡도를 감소시킬 수 있을 뿐만 아니라 움직임 끊김 현상을 효과적으로 제거함으로써 동영상의 재생 시 주관적 화질이 크게 떨어지지 않음을 확인할 수 있다.

• Journal of Electrochemical Science and Technology
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• 제11권2호
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• pp.99-116
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• 2020

The article provides information on ceramic / nanostructured materials which are suitable for solid oxide fuel cells (SOFCs) working between 500 to 1000℃. However, low temperature solid oxide fuel cells LTSOFCs working at less than 600℃ are being developed now-a-days with suitable new materials and are globally explored as the "future energy conversion devices". The LTSOFCs device has emerged as a novel technology especially for stationary power generation, portable and transportation applications. Operating SOFC at low temperature (i.e. < 600℃) with higher efficiency is a bigger challenge for the scientific community since in low temperature regions, the efficiency might be less and the components might have exhibited lower catalytic activity which may result in poor cell performance. Employing new and novel nanoscale ceramic materials and composites may improve the SOFC performance at low temperature ranges is most focused now-a-days. This review article focuses on the overview of various ceramic and nanostructured materials and components applicable for SOFC devices reported by different researchers across the globe. More importance is given for the nanostructured materials and components developed for LTSOFC technology so far.

• 한국세라믹학회지
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• 제55권5호
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• pp.407-418
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• 2018

Increasing demand for portable and wireless electronic devices with high power and energy densities has inspired global research to investigate, in lieu of scarce rare-earth and expensive ruthenium oxide-like materials, abundant, cheap, easily producible, and chemically stable electrode materials. Several potential electrode materials, including carbon-based materials, metal oxides, metal chalcogenides, layered metal double hydroxides, metal nitrides, metal phosphides, and metal chlorides with above requirements, have been effectively and efficiently applied in electrochemical supercapacitor energy storage devices. The synthesis of self-grown, or in-situ, nanostructured electrode materials using chemical processes is well-known, wherein the base material itself produces the required phase of the product with a unique morphology, high surface area, and moderate electrical conductivity. This comprehensive review provides in-depth information on the use of self-grown electrode materials of different morphologies in electrochemical supercapacitor applications. The present limitations and future prospects, from an industrial application perspectives, of self-grown electrode materials in enhancing energy storage capacity are briefly elaborated.

• 전기전자학회논문지
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• 제18권2호
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• pp.198-205
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• 2014

정보화 기술의 발전에 따라 웨어러블 장치, 휴대용 장치, RFID와 같은 소형 애플리케이션에 대한 관심이 증가하고 있고, 여기에 적용하기 위한 소형 암호화 회로의 중요성이 강조되고 있다. 본 논문에서는 소형 애플리케이션에 적합한 AES 기반 암호화 회로를 제안한다. 제안하는 회로에서는 저장 공간의 최소화, 연산 자원의 공유를 통해서 크기를 최소화 하였다. 제안하는 회로는 $8{\times}16$ 비트 크기의 SRAM 두 개를 사용하였으며, 65nm 표준 셀 라이브러리를 이용하여 합성한 결과 2,241 개의 게이트로 구현되었고, 처리 속도는 초당 50.57M 비트이다. 따라서 저면적 암호화 회로를 필요로 하는 다양한 애플리케이션에 적용하여 사용할 수 있다.

• 한국통신학회논문지
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• 제42권4호
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• pp.889-891
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• 2017

LED 조명을 활용한 통신인 가시광통신 기술은 IEEE 802.15.7 WG에 의해 정의되었고 활발한 연구가 진행 중이다. 가시광통신은 기존 RF 통신과의 간섭을 회피할 수 있는 장점 뿐 아니라, LOS(Line of Sight) 특성을 활용하여 정확한 측위를 통한 위치기반 서비스를 제공할 수 있어 사용자의 위치를 확인하고 추적하는데 매우 용이하다. 본 논문에서는 LED 조명을 이용한 위치측정에 휴대기기를 쉽게 적용할 수 있도록, UBS 인터페이스를 이용한 가시광통신 송수신기를 구현하였다. 인터넷 프로토콜을 통해 휴대기기의 이동성을 지원했으며 보행 중 조명과 스마트 기기의 높이인 1m 이상에서 $10^{-3}dBm$이하의 BER 성능을 보였다.

• 한국환경보건학회지
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• 제40권3호
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• pp.171-177
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• 2014

Background: The development of technology can be beneficial for the life and health of human society. Crowdsourcing refers to drawing upon a large pool of individuals in order to seek services, ideas, or other contributions. With the development of information communication technology, crowdsourcing is able to provide powerful results in environmental health research. Methods: We searched 'crowdsourcing' and 'citizen science' for keywords related to the environmental health field and only selected journal articles and conference proceedings material, such as research reports and WHO reports. Results: This paper reviewed environmental health research using crowdsourcing. Examples of such research based on crowdsourcing included practices in environmental disasters, noise monitoring, global positioning system (GPS) technology, smart phones, attached portable devices and information delivery by web. Crowdsourcing methods can provide notably distinct approaches for future environmental health research. However, it is also important to protect personal information whenever crowdsourcing is applied to data generation and information dissemination. Conclusion: We expect that this review may provide useful information for the development of new environmental health research methods using crowdsourcing and citizen science.

• 센서학회지
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• 제31권6호
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• pp.418-422
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• 2022

α-pinene is a natural volatile organic compound secreted by coniferous trees to protect themselves from attacks by insects, microorganisms, and viruses. Recently, studies have reported that α-pinene possesses pharmacological effects on various biological reactions such as anxiolytic, sleep-enhancing, anti-nociceptive, and inflammatory activity. Thus, forest bathing has recently received great attention as a novel therapy for treating severe diseases as well as psychological issues. However, appropriate places and timings for effective therapies are still veiled, because on-site monitoring of α-pinene gas in forests is barely possible. Although portable chemosensors could allow real-time analysis of α-pinene gas in forests, the α-pinene sensing properties of chemosensors have never been reported thus far. Herein, we report for the first time, the α-pinene sensing properties of an oxide semiconductor gas sensor based on rhombohedral In₂O₃ (h-In₂O₃) nanoparticles prepared by a microwave-assisted hydrothermal reaction. The h-In₂O₃ nanoparticle sensor showed a high response to α-pinene gas at ppm levels, even under humid conditions (for example, relative humidity of 50 %). The purpose of this research is to identify the potential of oxide semiconductor gas sensors for implementing portable devices that can detect α-pinene gas in forests in real-time.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2005년도 추계종합학술대회
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• pp.529-532
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• 2005

In this paper, we propose a motion picture processor for CSTN LCD. In order to eliminate flicker phenomenon, the proposed processor suggests a new driving scheme, SFP(Subgroup Frame Pattern). We use an input image compression methode from RGB(:8:8;8) to RGB(5:6:5) to improve quality of the image and apply the image to CSTN Module. The proposed hardware architecture has been implemented and verified using a FPGA on prototype board. The proposed Algorithm provide a lower computational complexity. Therefore the processor can be used in the display devices such as PDA, mobile phone and PMP(Portable Multimedia Player).

• Journal of Biosystems Engineering
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• 제41권2호
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• pp.116-125
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• 2016

Background: Microfluidics is of considerable importance in food and agricultural industries. Microfluidics processes low volumes of fluids in channels with extremely small dimensions of tens of micrometers. It enables the miniaturization of analytical devices and reductions in cost and turnaround times. This allows automation, high-throughput analysis, and processing in food and agricultural applications. Purpose: This review aims to provide information on the applications of microfluidics in the agro-food sector to overcome limitations posed by conventional technologies. Results: Microfluidics contributes to medical diagnosis, biological analysis, drug discovery, chemical synthesis, biotechnology, gene sequencing, and ecology. Recently, the applications of microfluidics in food and agricultural industries have increased. A few examples of these applications include food safety analysis, food processing, and animal production. This study examines the fundamentals of microfluidics including fabrication, control, applications, and future trends of microfluidics in the agro-food sector. Conclusions: Future research efforts should focus on developing a small portable platform with modules for fluid handling, sample preparation, and signal detection electronics.