• Microbiology and Biotechnology Letters
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• v.5 no.3
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• pp.133-140
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• 1977

The results of electron microscopic studies on the cell fine structure of Nocardia sp the location of tellurite-reducing enzyme and the reduction part of T. T. C. (Triphenyl tetrazonium chloride) were summarized as follows. As the fine structure of the cell, the membrane-like structure with unit membrane was distributed in the cytoplasm. The membrane-like structure had complicate forms: some of membrane-like structure appeared spiral form. As the metal tellurium salt appeared in the cytoplasm, it is obvious that tellurite and tellurate-reducing enzymes are present in the cytoplasm. Reduction of T. T. C. took place in the cell membrane and the intracellular membrane-like structure. Therefore, it was thought that reduction of tellurate and T. T. C. took place in different parts. T. T. C. formazane formed in the cell was reoxidized by osmic acid which was used as a fixation reagent for the electron microscopic specimen preparation. As 95％ T. T. C. formazane was soluble in ethanol and embedding materials and removed out of the cell, an originally formed formazane appeared as electron light part on the electron microscopic image.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.4
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• pp.211-218
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• 2018

Recently, various technologies related to IIoT are introduced continuously due to the spread of IoT and smart factory industries. This paper proposes the construction of a two-way wireless network system for monitoring plant equipment using these various technologies. The main technologies used in this thesis are design techniques for micro sensor nodes to monitor facility conditions at various sites, MQTT technology for wireless communication between local server and sensor nodes and Node-RED based design technologies, which store data collected and can be easily presented to users via wired and wireless wires. In addition, a wireless two-way camera system was also implemented in which the screen images of the site can be viewed in the situation room according to the instructions of the situation room when determining abnormal conditions.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.325-325
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• 2008

스크린 프린팅에 의한 압전 후막은 MEMS 공정을 이용하여 마이크로 펌프, 마이크로 벨브, 마이크로 센서, 마이크로 로봇 등 여러 초소형 기계부품에 응용되고 있으며, Sol-Gel, PLD를 이용해 증착된 막 등에 비해 수십${\mu}m$의 비교적 두꺼운 막을 형성시킬 수 있는 장점을 가지고 있다. 그러나 실리콘 기판을 사용하여 스크린 프린팅으로 형성된 압전 후막의 경우, 공정상 바인더를 연소시키는 과정을 거치게 되므로, 밀집된(Dense) 구조를 가지는 막을 만들기가 어렵다. 이로 인해 스크린 프린팅에 의한 후막은 전기적 특성 및 기계적 특성이 떨어지는 경향이 있다. 본 연구에서는 스크린 프린팅에 의한 압전 후막의 밀집된 구조 및 특성을 향상시키기 위해 0.01Pb$(Mg_{1/2}W_{1/2})$O3-0.41Pb$(Ni_{1/3}Nb_{2/3})O_3-0.35PbTiO_3-0.23PbZrO_3$의 powder와 Attrition 밀링 처리된 powder를 비율별로 혼합하여 입자의 크기를 변화시켜 막의 충진 밀도를 향상시켰으며, 열처리 효과를 극대화시키기 위해 RTA(Rapidly Thermal Annealing)를 통해 열처리 하였다. Attrition 밀링에 의한 파우더를 각각 비율별로 100%, 50%, 25%로 혼합하여 만든 압전 세라믹 페이스트는 P-type(100)Si Wafer sample 위에 $1{\mu}m$의 하부전극용($1100^{\circ}C$) Ag 전극을 screen print하여 소결했다. 그리고 다시 전극이 형성된 Si wafer 위에 스크린 프린팅하고, 건조 한 후 RTA로 300초 동안 열처리 한 결과 밀집된 구조를 가지는 압전 후막을 제작 수 있었다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.2
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• pp.99-113
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• 1992

In general, TDMA and FDMA have been used for multiple access communication methods. Recently. However, ALOHA and CSMA protocols came to exist as new schemes for VSAT data networks and LANs, respectively. These schemes are proven to be effective for packet switched communication systems that has bursty traffic but packet collisions. In this paper we analyze capture statistics arising from fading channels in packet radio communication systems in the context of ALOHA protocol. We derive general results of the exact form of capture probabilities and present numerical data for wide range of fading parameters. Since the capture probabilities are found to approach zero when the number of transmitted signals become larger, we are able to determine the achievable channel throughput by a least squares fitting of an exponential-type function to the probabilities.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.5
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• pp.1093-1100
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• 2018

Fast progress in miniaturization and reducing power consumption of semiconductors for wearable devices makes it possible to develop extremely small wearable systems for various application services. This results recent wearable applications to be powered from extremely low-power energy harvesters based on solar, piezo, and TENG sources. In most cases, the harvesters generate power in non-linear manner. Therefore, we implemented and experimented the device platforms to utilize natural frequency of around 3Hz. We also designed two-stage power storages and high efficiency conversion platform to consider such non-linear power harvesting sources. The experiment showed power generation of about 4.67mW/min from these non-linear sources with provision of stable energy storages.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.11B
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• pp.685-692
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• 2007

Recent advances in wireless communications and electronics have enabled the development of low-cost, low-power, multi-functional sensors. A typical wireless sensor network (WSN) consists of a large number of sensor nodes that can measure and process data while communicating through wireless channels. In this paper, we propose a hybrid query processing (HQP) algorithm for user queries submitted to the WSN. Unlike previous algorithms that consider continuous queries only, HQP supports both continuous queries and ad-hoc queries. Specially. HQP tries to reduce energy consumption of ad-hoc queries by using query results cached at each sensor node which are created during the execution of the previous continuous query. HQP can also exploit a trade-off between energy consumption and data accuracy. We evaluate the performance of HQP under a variety of WSN configurations.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.3
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• pp.47-56
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• 2005

This paper presents a performance improvement result with the aid of closed feedback controller loop to a micro gyroscope. The dynamic model of a micro gyroscope is derived and a conventional proportional and derivative controller is designed via frequency domain analysis. The proposed control loop is implemented using several analog devices and applied to the SNU-Bosch MEMS gyroscope to check its performance improvement in real environment. The experiments demonstrated the performance improvement with the proposed feedback control loop. The bandwidth, linearity, and bias stability are improved to 78 Hz, 0.504 %, and 0.043 deg/sec, respectively, from 35 Hz, 2.07 %, and 0.066 deg/sec of open loop system.

• Bulletin of the Korean Space Science Society
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• 2010.04a
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• pp.37.5-38
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• 2010

경희대학교 우주탐사학과에서는 우주공간 탐사를 위해 Trio(TRiplet Ionospheric Observatory)-CINEMA(Cubesat for Ions, Neutrals, Electrons and MAgnetic fields)로 명명된 초소형 위성을 개발하고 있다. 과학임무는 지구 저궤도에서 고에너지 입자를 관측하는 것이며, 이를 위해 고에너지 (2~300keV) 입자 검출기와 자기장 측정기가 탑재된다. 저에너지 입자 검출기 시스템인 STEIN(SupraThermal Electrons, Ions, Neutrals)은 $1\times4$ Array의 개선된 실리콘 검출기와 이온, 전자, 중성입자를 분리할 수 있는 정전장 편향기, 그리고 신호를 처리하는 전자회로로 구성되어있다. 설계된 전자회로는 매우 작은 검출기 기판, 아날로그 기판과 디지털 기판으로 이루어져 있고, 475mW 이하의 저 전력으로 동작한다. 또한 2~100keV의 에너지를 1keV이하의 해상도로 30,000event/sec/pixel 까지 관측 할 수 있도록 회로를 설계하였다. 센서로 들어온 입자로 인해 발생한 펄스의 신호는 4개의 아날로그 회로가 담당하게 되는데, Folded cascode amplifier를 배치하여 증폭률을 높인 Charge sensitive amplifier를 통해 신호를 증폭하고, $2{\mu}s$ unipolar gaussian shaping amplifier를 통해 읽기 쉽게 처리된 신호를 상한파고선별기와 하한파고 선별기를 통해 유효 값 여부를 판단하고, 피크 검출기를 통해 피크의 타이밍을 측정한 뒤 신호를 아날로그-디지털 변환 회로를 통하여 8bit의 값으로 나타내어, 입자들의 Spectrum을 측정하게 된다. 크기와 소비전력이 적음에도 검출성능이 우수하기 때문에 이 시스템은 향후 우주탐사 시스템에 있어 매우 중요한 역할을 수행 할 것으로 생각한다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.517-520
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• 2009

Healthcare application system has been actively researched to apply WSN technology to healthcare area with a mobile sensor node of low cost, low power, and small size. Sensor node has the problem for transmission range of RF power and time delay of the wireless routing connectivity between sensor nodes. In this paper, we proposes a new method utilizing mobile sensor nodes with relay sensor nodes for quick network routing changing using query technique in healthcare system. A query processor to control and manage the routing changing of sensor nodes in a wireless sensor network was designed and implemented. The user's PC transmits the beacon message which will change the quick link routing according to activity status of patient in wireless sensor network. We describe the implementation for query protocol that is very effective of power saving between sensor nodes.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.12
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• pp.1645-1652
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• 2018

A drone which was developed first for military purpose has been expanded to various civil areas, with its technological development. Of the drones developed for such diverse purposes, a drone for photography has a camera installed and is actively applied to a variety of image contents making, beyond filming and broadcasting. A drone for photography makes it possible to shoot present and dynamic images which were hard to be photographed with conventional photography technology. This study made a view finder which helps a drone operator to control a drone and directly view an object to shoot with the drone camera. The view finder for drones is a type of glasses. It was developed in the way of printing out the data modelled with 3D MAX in a 3D printer and installing a ultra-small LCD monitor. The view finder for drones makes it possible to fly a drone safely and achieve accurate framing of an object to shoot.