• 문화기술의 융합
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• 제3권4호
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• pp.181-184
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• 2017

우리나라는 세계 10대 에너지 소비국으로서 총에너지의 97%를 해외 수입에 의존하며 2007년 에너지 수입액은 950억불로 전체 수입액의 26.6%를 차지함으로써 2008년과 같은 에너지 위기에 대하여 근본적이며 장기적인 대책 수립이 절실히 요구되고 있는 실정이다. 전 세계적으로 에너지 절감과 저탄소 경제 시대 대응을 위해 세계 각국이 발빠르게 움직이고 있음에도 불구하고 국내의 움직임은 상대적으로 더디게 진행되고 있다. 이에 본 논문에서는 병원 시설물을 가정 하에 중대형 시설물에 구축된 Light Things(조명, 사이니지, 디스플레이 등) 제어를 위한 IoT 데이터 수집장치(Gateway)를 개발함으로써, Light Things로 인해 소비되는 에너지 소비율을 효과적으로 제어할 수 있는 Light Things 제어 알고리즘 및 데이터 수집장치(Gateway) 개발 기술에 대하여 제안한다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2006년도 전력전자학술대회 논문집
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• pp.203-205
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• 2006

This paper presents a novel soft-switching PWM utility frequency AC to high frequency AC power conversion circuit incorporating boost-half-bridge inverter topology, which is more suitable and acceptable for cost effective consumer induction heating applications. The operating principle and the operation modes are presented using the switching mode and the operating voltage and current waveforms. The performances of this high-frequency inverter using the latest IGBTs are illustrated, which includes high frequency power regulation and actual efficiency characteristics based on zero voltage soft switching (ZVS) operation ranges and the power dissipation as compared with those of the previously developed high-frequency inverter. In addition, a dual mode control scheme of this high frequency inverter based on asymmetrical pulse width modulation (PWM) and pulse density modulation (PDM) control scheme is discussed in this paper in order to extend the soft switching operation ranges and to improve the power conversion efficiency at the low power settings. The power converter practical effectiveness is substantially proved based on experimental results from practical design example.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.115-116
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• 2012

The demand for flexible electronic systems such as wearable computers, E-paper, and flexible displays has increased due to their advantages of excellent portability, conformal contact with curved surfaces, light weight, and human friendly interfaces over present rigid electronic systems. This seminar introduces three recent progresses that can extend the application of high performance flexible inorganic electronics. The first part of this seminar will introduce a RRAM with a one transistor-one memristor (1T-1M) arrays on flexible substrates. Flexible memory is an essential part of electronics for data processing, storage, and radio frequency (RF) communication and thus a key element to realize such flexible electronic systems. Although several emerging memory technologies, including resistive switching memory, have been proposed, the cell-to-cell interference issue has to be overcome for flexible and high performance nonvolatile memory applications. The cell-to-cell interference between neighbouring memory cells occurs due to leakage current paths through adjacent low resistance state cells and induces not only unnecessary power consumption but also a misreading problem, a fatal obstacle in memory operation. To fabricate a fully functional flexible memory and prevent these unwanted effects, we integrated high performance flexible single crystal silicon transistors with an amorphous titanium oxide (a-TiO2) based memristor to control the logic state of memory. The $8{\times}8$ NOR type 1T-1M RRAM demonstrated the first random access memory operation on flexible substrates by controlling each memory unit cell independently. The second part of the seminar will discuss the flexible GaN LED on LCP substrates for implantable biosensor. Inorganic III-V light emitting diodes (LEDs) have superior characteristics, such as long-term stability, high efficiency, and strong brightness compared to conventional incandescent lamps and OLED. However, due to the brittle property of bulk inorganic semiconductor materials, III-V LED limits its applications in the field of high performance flexible electronics. This seminar introduces the first flexible and implantable GaN LED on plastic substrates that is transferred from bulk GaN on Si substrates. The superb properties of the flexible GaN thin film in terms of its wide band gap and high efficiency enable the dramatic extension of not only consumer electronic applications but also the biosensing scale. The flexible white LEDs are demonstrated for the feasibility of using a white light source for future flexible BLU devices. Finally a water-resist and a biocompatible PTFE-coated flexible LED biosensor can detect PSA at a detection limit of 1 ng/mL. These results show that the nitride-based flexible LED can be used as the future flexible display technology and a type of implantable LED biosensor for a therapy tool. The final part of this seminar will introduce a highly efficient and printable BaTiO3 thin film nanogenerator on plastic substrates. Energy harvesting technologies converting external biomechanical energy sources (such as heart beat, blood flow, muscle stretching and animal movements) into electrical energy is recently a highly demanding issue in the materials science community. Herein, we describe procedure suitable for generating and printing a lead-free microstructured BaTiO3 thin film nanogenerator on plastic substrates to overcome limitations appeared in conventional flexible ferroelectric devices. Flexible BaTiO3 thin film nanogenerator was fabricated and the piezoelectric properties and mechanically stability of ferroelectric devices were characterized. From the results, we demonstrate the highly efficient and stable performance of BaTiO3 thin film nanogenerator.

• 산업경영시스템학회지
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• 제39권3호
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• pp.170-179
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• 2016

In this paper we have tackled the outstanding inventory planning problems over new product launching period in a more holistic manner by addressing first the definition of efficient business rules to effectively control and reduce the inventory risks followed by the rigorous explanations on the implementation guide on suggested inventory planning rules. It is not unusual for many companies in the consumer electronics market to make a great effort to reduce the time to launch a new product because the ability to bring out higher performing products in such a short time period greatly increases the probability for them to remain competitive in the high tech market. Among so many newly developed products, those products with new features and technologies appeal to many potential customers while products which fail to win customers by design and prices rapidly disappear in the market. To adapt to this business environment, those companies have been trying to find the answer to minimize the inventory of old products so they can move to next generation products quickly with less obsolete material. In the experimental implementation of our rule-based inventory planning, Company 'S' reduced the inventory cost for the outgoing products as low as 49% of its peak level of its preceding product version in just 5 month after the adoption of rule-based inventory planning process and system. This paper concluded the subject with a suggestion that the best performance of rule-based inventory planning is guaranteed not from one-time campaign of process improvement along with system development but the decision maker's continuing support and attention even without seeing any upcoming business crisis.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제5권4호
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• pp.720-740
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• 2011

Wi-Fi-enabled portable devices have recently been introduced into the consumer electronics market. These devices download or upload content, from or to a host machine, such as a personal computer, a laptop, a home gateway, or a media server. This paper investigates the fairness among multiple Wi-Fi-enabled portable devices in a home network when they are simultaneously communicated with the host machine. First, we present that, a simple IEEE 802.11-based home network suffers from unfairness, and the fairness is exaggerated by the wireless link errors. This unfairness is due to the asymmetric response of the TCP to data-packet loss and to acknowledgment-packet loss, and the wireless link errors that occur in the proximity of any node; the errors affect other wireless devices through the interaction at the interface queue of the home gateway. We propose a QoS-provisioning framework in order to achieve per-device fairness and service differentiation. For this purpose, we introduce the medium access price, which denotes an aggregate value of network-wide traffic load, per-device link usage, and per-device link error rate. We implemented the proposed framework in the ns-2 simulator, and carried out a simulation study to evaluate its performance with respect to fairness, service differentiation, loss and delay. The simulation results indicate that the proposed method enforces the per-device fairness, regardless of the number of devices present and regardless of the level of wireless link errors; furthermore it achieves high link utilization with only a small amount of frame losses.

• 한국정보전자통신기술학회논문지
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• 제11권1호
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• pp.45-53
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• 2018

신재생 에너지원 등 분산전원의 확산에 따라 단순한 소비자에서 적극적으로 에너지 거래를 원하는 프로슈머에 대한 논의가 확산되고 있다. 프로슈머는 잉여 에너지 혹은 분산자원을 이용하여 생산한 에너지를 전력회사, 다른 에너지 사업자 및 타 수용가에 판매할 수 있는 새로운 형태의 소비자이다. 이러한 개념을 지원하기 위해서는 프로슈머의 거래를 지원할 수 있는 기술과 플랫폼이 필요하나 이에 대한 연구는 시작 단계에 있다. 본 논문은 거래기반 에너지 관리를 위한 대표적인 기술의 비교분석을 통하여 향후 거래기반 에너지 관리 기술의 진화 방향에 대하여 검토하였다. 아직 거래기반 에너지를 충실하게 지원할 수 있는 기술이나 표준은 정립되지 않은 단계로 기술간 경쟁을 통해 지속적으로 발전해 나갈 것으로 예상된다.

• 한국정보통신학회논문지
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• 제5권7호
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• pp.1238-1244
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• 2001

광대역 액세스 망에서 합류, 분배 지점에서의 효율을 고려한 광 수동망 설계는 중요하다. 광수동망 구조는 매우 간단하지만, 가입자들에서 발생되는 상향 트래픽 제어를 위해서는 매체 접근 제어 프로토콜이 필요하다. 한편, 사무실 환경을 위한 통신규약은 이미 표준화되어 있다. 광대역 통신망과 다양한 가전 제품의 증가에 의해 홈 네트워크 구성은 자연스러운 일이 되었다. 가정에서 사용하는 네트워크 응용 범위가 넓어짐에 따라 액세스 망과 여러 형태의 트래픽을 발생시키는 홈 네트워크 환경을 고려하였다. Global-FIFO 는 매우 간단하고, 기본적으로 요추-허용 메카니즘의 동적인 상향 대역 할당방식을 사용한다. 이것은 셀을 기본 단위로 한 효율적인 대역을 사용할 수는 있지만, 다양한 형태의 트래픽을 취급하는 홈 네트워크에는 적합하지 않다. 본 논문에서, 우리는 ATM-PON과 홈 네트워크 환경에 적합한 성능을 제어하는 MQ-FIFO라는 새로운 자원할당 MAC 알고리즘을 설계하고 분석한다.

• Safety and Health at Work
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• 제2권1호
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• pp.34-38
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• 2011

Objectives: The antimicrobial activity of silver nanoparticles has resulted in their widespread use in many consumer products. Yet, despite their many advantages, it is also important to determine whether silver nanoparticles may represent a hazard to the environment and human health. Methods: Thus, to evaluate the genotoxic potential of silver nanoparticles, in vivo genotoxicity testing (OECD 474, in vivo micronuclei test) was conducted after exposing male and female Sprague-Dawley rats to silver nanoparticles by inhalation for 90 days according to OECD test guideline 413 (Subchronic Inhalation Toxicity: 90 Day Study) with a good laboratory practice system. The rats were exposed to silver nanoparticles (18 nm diameter) at concentrations of $0.7\;{\times}\;10^6$ particles/$cm^3$ (low dose), $1.4\;{\times}\;10^6$ particles/$cm^3$ (middle dose), and $2.9\;{\times}\;10^6$ particles/$cm^3$ (high dose) for 6 hr/day in an inhalation chamber for 90 days. The rats were killed 24 hr after the last administration, then the femurs were removed and the bone marrow collected and evaluated for micronucleus induction. Results: There were no statistically significant differences in the micronucleated polychromatic erythrocytes or in the ratio of polychromatic erythrocytes among the total erythrocytes after silver nanoparticle exposure when compared with the control. Conclusion: The present results suggest that exposure to silver nanoparticles by inhalation for 90 days does not induce genetic toxicity in male and female rat bone marrow in vivo.

• 한국통신학회논문지
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• 제35권6B호
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• pp.970-976
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• 2010

방송과 통신의 융합으로 시작된 미디어 플랫폼간의 융합은 이제 다양한 컨버전스 서비스를 창출하기 위한 S/W 생태계 구축을 시작으로 IT 및 비IT를 망라하여 전 업종으로 융 복합화를 앞당기고 있다. 이러한 컨버전스 환경의 대두와 함께 가정 및 산업용, 그리고 다양한 환경에서의 기기간 자동화 및 연결을 통한 새로운 부가 서비스를 창출하려는 RF4CE (Radio Frequency for Consumer Electronics) 기술이 대두되고 있으며, 본 논문에서는 기기간 효율적인 연결 및 제어를 위해 활용될 수 있는 ZigBee 표준화 기구의 RF4CE 기술에서의 향상된 키 교환 스킴에 대한 방안을 제시하였다. 제시된 방안은 기기간 상호 인증 및 두 단계의 Key Seed 분배 기법 등으로 구성되어 있으며, 본 논문에서는 제안 방안의 분석 및 실제 구현 및 실험을 통해 그 유용성을 검증하였다.

• Toxicological Research
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• 제27권2호
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• pp.61-70
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• 2011

Brominated flame retardants (BFRs) are present in many consumer products ranging from fabrics to plastics and electronics. Wide use of flame retardants can pose an environmental hazard, which makes it important to determine the mechanism of their toxicity. In the present study, dose-dependent toxicity of tetrabromobisphenol A (TBBPA), a flame retardant, was examined in male prepubertal rats (postnatal day 18) treated orally with TBBPA at 0, 125, 250 or 500 mg/kg for 30 days. There were no differences in body weight gain between the control and TBBPA-treated groups. However, absolute and relative liver weights were significantly increased in high dose of TBBPA-treated groups. TBBPA treatment led to significant induction of CYP2B1 and constitutive androstane receptor (CAR) expression in the liver. In addition, serum thyroxin (T4) concentration was significantly reduced in the TBBPA treated group. These results indicate that repeated exposure to TBBPA induces drug-metabolising enzymes in rats through the CAR signaling pathway. In particular, TBBPA efficiently produced reactive oxygen species (ROS) through CYP2B1 induction in rats. We measured 8-hydroxy-2'-deoxyguanosine (8-OHdG), a biomarker of DNA oxidative damage, in the kidney, liver and testes of rats following TBBPA treatment. As expected, TBBPA strongly induced the production of 8-OHdG in the testis and kidney. These observations suggest that TBBPA-induced target organ toxicity may be due to ROS produced by metabolism of TBBPA in Sprague-Dawley rats.