• 한국기계가공학회지
• /
• 제8권2호
• /
• pp.10-17
• /
• 2009

Transillumination system used by radiation is widely applied to industrial imaging system. In this study, the linear detector array constructed with scintillator and pin diode, and a multi-channel data acquisition system was developed for precision inspection of end-milling. The detector module consists of $16-CdWO_4$crystal scintillator and photodiode array. The detector and data acquisition system was applied to precision inspection of end-mill and the images of the end-mill were successfully reconstructed. The total system can analyze the Detector Quantum Efficiency(DQE) of each system. The performance of developed photodiodes equipment was compared with each other for different crystal geometry and its characteristics. Finally fine details of the end-mill phantom were constructed for industrial application. The image acquired contains several objects on a real time data transfer and the linear X-ray scanning system can be applied to many fields of a industry.

• 한국태양에너지학회 논문집
• /
• 제32권spc3호
• /
• pp.245-254
• /
• 2012

In photovoltaic system, the characteristics of photovoltaic module such as open circuit voltage and short circuit current will be changed because of cell temperature and solar radiation. Therefore, the boost converter of a PV system connects between the output of photovoltaic system and DC link capacitor of grid connected inverter as controlling duty ratio for maximum power point tracking(MPPT). This paper shows the dynamic characteristics of the boost converter by comparing single-loop and two-loop control algorithm using both analog and digital control. Both proposed compensation methods have been verified with computer simulation to demonstrate the validity of the proposed control schemes.

• JSTS:Journal of Semiconductor Technology and Science
• /
• 제6권3호
• /
• pp.169-174
• /
• 2006

In this work, we demonstrate a novel compact mechanical beam steering transmitter based on a direct vertical integration of a 2-D MEMS-based mechanical beam steering antenna with a VCO on a single silicon platform. By eliminating the long feed lines and waveguide metal blocks, the radiation pattern has been improved vastly, resulting in an almost ideal pattern at every scan angle. The losses incurred by the feed lines and phase shifters are also eliminated, which allows the transmitter to be implemented using only a single VCO. The system complexity has been greatly reduced with a total module size of only 1.5 cm ${\times}$ 1.5 cm ${\times}$ 0.4 cm. This work demonstrates that RF MEMS can be a key enabling technology for high-level integration.

• 한국산학기술학회논문지
• /
• 제18권1호
• /
• pp.425-430
• /
• 2017

RFID는 무선 주파수를 이용하여 사물 또는 사람에 부착된 태그의 정보를 읽어내는 기술이다. 비접촉 방식으로 위치를 추적하는 RFID 시스템에서 태그를 이용하여 위치를 추적할 때 실제의 위치와 측정된 위치 간의 오차가 발생한다. 본 논문에서는 RFID 기술을 통한 사물 또는 사람의 위치를 파악하는 방법에 있어 3가지 방법을 제안한다. RFID기반의 위치 인식시스템을 구성하고 태그(tag)들을 정사각형 형태로 배치한다. 리더(reader)를 보유한 물체의 실제위치와 실험을 통해 예상되는 물체의 위치를 비교하여 오차를 확인한다. 기존 논문에서는 리더에 읽힌 모든 tag들의 무게중심 값을 구하여 리더의 대략적인 위치를 구하였다면 본 논문에서는 중점과 방사원의 형태를 이용하여 예상위치를 구하는 3가지 방법을 추가적으로 제시하는데 첫 번째는 중간 값을 사용한 방법, 두 번째는 방사 형태를 사용한 방법, 세 번째는 원과 중간 값을 절충한 방법을 사용하였다. 데이터를 통해 본 논문에서 제안된 4가지 방법 중 어떤 방법이 거리의 오차가 적어 실제 위치를 추적하는 데에 효율적인지 확인하고자 한다. 그 결과 방사형태, 중앙 값, 그리고 방사형태와 중앙 값 두 가지를 모두 이용한 방법 중 중앙 값 만을 이용한 계산 방법이 가장 적은 오차가 발생하였다.

• 센서학회지
• /
• 제25권2호
• /
• pp.131-137
• /
• 2016

In this study, a multilevel visible light communication (VLC) system based on resistor ladder circuit is designed to transmit medical data. VLC technology is being considered as an alternative wireless communication due to various advantages such as ubiquity, license free operation, low energy consumption, and no radio frequency (RF) radiation characteristics. With VLC even in places where traditional RF communication (e.g., Wi-Fi) is forbidden, significant bio-medical signal including the electrocardiography (ECG) and photoplethysmography (PPG) data can be transmitted. More lives could be saved anywhere by this potential advantage of VLC with a fast emergency response time. A multilevel transmission scheme is adopted to improve the data capacity with keeping simplicity, where data transmission rate can increase by log2m times (m is the number of voltage levels) than that of conventional VLC transmission based on on/off keying. In order to generate multi-amplitudes, resistor ladder circuit, which is a basic principle of digital to analog convertor, is employed, and information is transferred through LED (Light-Emitting Diode) with different voltage level. In the receiver side, multilevel signal is detected by optical receiver including a photo diode. Then, the collected data are analyzed to serve the necessary medical care to the concerned patient.

• Genomics & Informatics
• /
• 제4권4호
• /
• pp.161-166
• /
• 2006

The establishment of DNA microarray technology has enabled high-throughput analysis and molecular profiling of various types of cancers. By using the gene expression data from microarray analysis we are able to investigate diagnostic applications at the molecular level. The most important step in the application of microarray technology to cancer diagnostics is the selection of specific markers from gene expression profiles. In order to select markers of Immortalization and transformation we used c-myc and $H-ras^{V12}$ oncogene-transfected NIH3T3 cells as our model system. We have identified 8751 differentially expressed genes in the immortalization/transformation model by multivariate permutation F-test (95% confidence, FDR<0.01). Using the support vector machine algorithm, we selected 13 discriminative genes which could be used to predict immortalization and transformation with perfect accuracy. We assayed $H-ras^{V12}$-transfected 'transformed' cells to validate our immortalization/transformation dassification system. The selected molecular markers generated valuable additional information for tumor diagnosis, prognosis and therapy development.

• Journal of the Korean Data and Information Science Society
• /
• 제17권3호
• /
• pp.889-904
• /
• 2006

Our purpose is to ascertain, if possible, whether atomic bomb survivors with cataracts and epilation were more radiosensitive than those survivors with cataracts but without epilation. A major ophthalmologic survey was conducted in Hiroshima and Nagasaki in 1963-64. At that time, 2125 individuals were examined. Among these individuals, estimated eye organ doses, based on the DS86 dosimetry system, and information on the occurrence of epilation within the first 60 days following the bombings are available on 1742. In the analysis of these data we have assumed that each individual represents a sample of one from a binomial distribution, and that the occurrence of cataracts and epilation are independent biological phenomena. We got following results. The threshold for cataract induction and its 95% confidence limits have been estimated from data on the occurrence of cataract and epilation. Among the 1742 study subjects, 40 had both cataracts and severe epilation. The estimated threshold based on these cases is 0.98 sievert(Sv), with 95% lower and upper confidence bounds of 0.72, and 1.32 Sv, respectively, and is highly statistically significant. Among the 27 cases of cataracts where severe epilation was not reported, the estimated threshold is 1.74 Sv with 95% lower and upper confidence bounds of 1.21 Sv, and "not estimable". The difference between these two estimates is not statistically significant although the effect of dose is highly significant in both instances. The potential importance of biases in the DS86 dose estimates is discussed. The difference between the threshold estimated from cataract cases with epilation and that from cases without epilation is not statistically significant at the 5% or 10% level, and thus affords no support for the notion of increased radiosensitivity.

• Journal of Electrical Engineering and Technology
• /
• 제10권3호
• /
• pp.1174-1180
• /
• 2015

We investigate in this paper the radiated electromagnetic waves together with the discharge characteristics of Trichel pulse of negative DC corona discharge in air in pin-to-plate and wire-to-plate configurations. The feature of the current pulse and the frequency spectrum of the electromagnetic radiations were measured under various pressures and gas gaps. The results show that the repetition frequency and the amplitude of Trichel pulse current depend on the discharge conditions, but the rising time of the pulse relates only to the radius of needle or wire and keeps constant even if the other conditions (including the discharge current, the gas gap and the gas pressure) change. There exists the characterized spectrum of electromagnetic waves from negative corona discharge in Trichel pulse regime. These characterized radiations do not change their frequency at a given cathode geometry even if the averaged current, the gas gap or the air pressure changes, but the amplitude of radiations changes accordingly. The characterized electromagnetic radiations from Trichel pulse corona relate to the formation or the rising edge of current pulse. It confirms that the characterized radiations from Trichel pulse supply information of discharge system and provide a potential method for detecting charged targets.

• 한국항공우주학회지
• /
• 제47권10호
• /
• pp.728-737
• /
• 2019

본 연구에서는 초소형 위성을 이용한 위성 편대 및 군집 운용 시 실시간으로 위성 간의 상대 위치 정보를 제공할 수 있는 통합 항법용 모듈형 온보드 컴퓨터(On-board Computer, OBC)를 개발하였다. 모듈은 구조적으로는 큐브위성의 기준 규격에 맞게 설계하되 사용자가 원하는 무선 통신모듈 및 항법용 Global Positioning System(GPS) 장비를 적용할 수 있도록 확장성을 고려하였다. 개발된 OBC는 제품 개발 및 제작 이후 야외 테스트를 통해 저전력 Micro Controller Unit(MCU)로 군집 운용을 수행하는 초소형 위성들의 통합 항법 및 실시간 데이터 동기화 요구 처리속도를 만족함을 확인하였다. 또한, 열진공, 방사능 시험을 거쳐 우주급 환경에서 정상 작동함을 확인하였으며, 진동시험의 경우 underfill 공정을 추가하면 정상적으로 요구조건을 만족할 수 있음을 확인하였다. 이를 통해 향후 수요가 늘어날 군집 운용을 위한 위성군 개발의 핵심 부품인 OBC의 대량생산 체계를 구축하였다.

• 한국정보전자통신기술학회논문지
• /
• 제3권1호
• /
• pp.24-30
• /
• 2010

본 논문에서는 전기적 소형 모노폴 형태의 안테나가 제시되었다. 크기가 매우 짧은 (${\iota}{\approx}{\lambda}_g/15$ ) 모노폴은 용량성 소자로 동작하며, 접지면 위에 놓여진 개방형 슬롯구조는 유도성 소자로 동작하므로, 이 들 두 소자를 결합시킨 구조는 LC 공진기를 형성하게 된다. 안테나에 대한 등가회로 모델 은 안테나의 해석 및 설계의 정확성을 파악하기 위하여 사용되었다. 제안된 안테나는 매우 작은 전기적인 크기를 갖고 있으나 양호한 성능을 나타내고 있다. 측정된 안테나의 최대 이득과 효율은 주파수 2.1 GHz에서 각각 3.6 dBi 및 77.8 %를 나타내었다.