• 한국광학회지
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• 제34권3호
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• pp.106-116
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• 2023

본 논문에서는 가시광선과 원적외선 전반의 파장대역에 걸쳐 사용 가능한 동축 듀얼카메라를 설계 및 분석하였다. 광학계는 빔 스플리터를 이용한 동축광학계 시스템으로 설계되었으며, 가시광선 광학계에서 적외선으로 인한 열 전달을 최소화하기 위해 hot mirror 타입의 빔 스플리터를 사용하였다. 원적외선 카메라는 비냉각형 검출기로 640×480의 센서 배열을 가지고, 가시광선은 1,945×1,097의 센서를 사용한다. 최적화 과정을 거친 후 최종 설계된 광학계의 정합도는 90% 이상이며, 기존에 존재하던 듀얼카메라에 비해 정합도가 향상된 효율적인 설계 결과를 얻었고, 테스트를 통해 향상된 정합도를 확인하였다.

• 한국방사선학회논문지
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• 제17권7호
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• pp.1197-1205
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• 2023

본 연구에서는 영남지역 해수욕장의 모래 시료 중에 함유되어 있는 방사능 농도를 측정하였다. 해수욕장에서 채취한 모래 표본은 영남지역의 유명해수욕장 8곳을 대상으로 선정하였다. 모래 표본을 반도체검출기인 고순도게르마늄검출기(HPGe)에 넣어 다채널분석기(MCA)를 이용한 정밀 감마 방사성핵종 분석을 실시했다. 방사선핵종의 농도를 측정하기 위해 측정 시간을 8,000 초로 설정하여 스펙트럼 파일을 얻어서 감마 방사성핵종의 농도를 분석하였다. 연구결과 8곳 해변 모두 TI-208의 방사능이 가장 높았다. 결론적으로 영남지역 해수욕장 모래표본에서 검출된 방사성핵종은 자연 방사성핵종이지만 인체 내부에 영향을 미칠 수 있다. 따라서 지속적으로 조사할 필요가 있다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제13권3호
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• pp.185-192
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• 2013

In this paper, a clock and data recovery (CDR) circuit that supports triple data rates of 1.62, 2.7, and 5.4 Gbps for DisplayPort 1.2 standard is described. The proposed CDR circuit covers three different operating frequencies with a single VCO switching the operating frequency by the 3-bit digital code. The prototype chip has been designed and verified using a 65 nm CMOS technology. The recovered-clock jitter with the data rates of 1.62/2.7/5.4 Gbps at $2^{31}$-1 PRBS is measured to 7/5.6/4.7 $ps_{rms}$, respectively, while consuming 11 mW from a 1.2 V supply.

• ETRI Journal
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• 제22권1호
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• pp.38-46
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• 2000

The extraction of model parameters for embedded passive components is crucial for designing and characterizing the performance of multichip module (MCM) substrates. In this paper, a method for optimizing the extraction of these parameters using genetic algorithms is presented. The results of this method are compared with optimization using the Levenberg-Marquardt (LM) algorithm used in the HSPICE circuit modeling tool. A set of integrated resistor structures are fabricated, and their scattering parameters are measured for a range of frequencies from 45 MHz to 5 GHz. Optimal equivalent circuit models for these structures are derived from the s-parameter measurements using each algorithm. Predicted s-parameters for the optimized equivalent circuit are then obtained from HSPICE. The difference between the measured and predicted s-parameters in the frequency range of interest is used as a measure of the accuracy of the two optimization algorithms. It is determined that the LM method is extremely dependent upon the initial starting point of the parameter search and is thus prone to become trapped in local minima. This drawback is alleviated and the accuracy of the parameter values obtained is improved using genetic algorithms.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2002년도 Proceedings
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• pp.208-210
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• 2002

In a treatment planning for actual patients with a complex internal structure, we often expect that proton beams, which pass through both a bolus and the heterogeneity in body, will form complex dose distributions. Therefore, the accuracy of the calculated dose distributions has to be verified for such a complex object. Then dose distributions formed by proton beams passing through both the bolus and phantoms simulating a clinical heterogeneity in patients were measured using a silicon semiconductor detector. The calculated results by the range-modulated pencil beam algorithm (RMPBA) produced large errors compared with the measured dose distributions since dose calculation using the RMPBA could not predict accurately the edge-scattering effect both in the bolus and in clinical heterogeneous phantoms. On the other hand, in spite of this troublesome heterogeneity, calculated results by the simplified Monte Carlo (SMC) method reproduced the experimental ones well. It is obvious that the dose-calculations by the SMC method will be more useful for application to the treatment planning for proton therapy.

• 동력기계공학회지
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• 제12권6호
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• pp.70-77
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• 2008

The purpose of this study is to compare the quality of digital radiography image with that of classical film images for welded structure in power plants. The CMOS(Complementary Metal Oxide Semiconductor) flat panel detecter and Agfa D5 film are used to image flaw specimens respectively. In the test, CMOS flat panel detector has been determined to have a better image than that of film image. In the IQI(Image Quality Indicator) transmission test, one or two more line can be seen in digital image than in film image. Digital Radiography Test enabled to successfully detect all defects on the weld specimens fabricated with real reheat stem pipe and boiler tube as well. In the specific comparison test, Digital radiography test detected micro flaws in the size of 0.5 mm in length by 0.5 mm in depth. However, film test has limited it to 1.0 mm in length by 1.0 mm in depth. As a result of this study, digital radiography technology is estimated well enough to perform the inspection in the industry with far more cost effective way, compared to the classical film test.

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2000년도 Proceedings of 5th International Joint Symposium on Microeletronics and Packaging
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• pp.29-33
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• 2000

MEMS, Micro Electro-Mechanical Systems, present one of the greatest advanced packaging challenges of the next decade. Historically hybrid technology, generally thick film, provided sensors and actuators while integrated circuit technologies provided the microelectronics for interpretation and control of the sensor input and actuator output. Brought together in MEMS these technical fields create new opportunities for miniaturization and performance. Integrated circuit processing technologies combined with hybrid design systems yield innovative sensors and actuators for a variety of applications from single crystal silicon wafers. MEMS packages, far more simple in principle than today's electronic packages, provide only physical protection to the devices they house. However, they cannot interfere with the function of the devices and often must actually facilitate the performance of the device. For example, a pressure transducer may need to be open to atmospheric pressure on one side of the detector yet protected from contamination and blockage. Similarly, an optical device requires protection from contamination without optical attenuation or distortion being introduced. Despite impediments such as package standardization and complexity, MEMS markets expect to double by 2003 to more than ＄9 billion, largely driven by micro-fluidic applications in the medical arena. Like the semiconductor industry before it. MEMS present many diverse demands on the advanced packaging engineering community. With focused effort, particularly on standards and packaging process efficiency. MEMS may offer the greatest opportunity for technical advancement as well as profitability in advanced packaging in the first decade of the 21st century! This paper explores MEMS packaging opportunities and reviews specific technical challenges to be met.

• 대한방사선기술학회지:방사선기술과학
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• 제23권2호
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• pp.75-79
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• 2000

This study was performed for the clinical applications applying the Monte Carlo methods. In this study we calculated the absorbed dose distributions for the 6 MeV electron beam in water phantom and compared the results with measured values. The energy data of electron beam used in Monte Carlo calculation is the energy distribution for 6 MeV electron beam which is assumed as a Gaussian form. We calculated percent depth doses and beam profiles for three field sizes of $10{\times}10,\;15{\times}15$, and $20{\times}20\;cm^2$ in water phantom using Monte Carlo methods and measured those data using a semiconductor detector and other devices. We found that the calculated percent depth doses and beam profiles agree with the measured values approximately. However, the calculated beam profiles at the edge of the fields were estimated to be lower than the measured values. The reason for that result is that we did not consider the angular distributions of the electrons in phantom surface and contamination of X-rays in our calculations. In conclusion, in order to apply the Monte Carlo methods to the clinical calculations we are to study the source models for electron beam of the linear accelerator beforehand.

• 한국인터넷방송통신학회논문지
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• 제12권1호
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• pp.181-187
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• 2012

LED는 빛을 내는 반도체 이다. 최근 친환경적 산업이 발전함에 따라 LED조명의 연구가 활발하게 진행되어 가고 있다. 특히 LED를 이용한 통신기법인 LED 통신에 대한 활발한 연구가 진행 중이다. 본 논문에서는 LED 통신을 이용한 PC-PC 전송시스템을 구현하였다. LED를 이용한 송신부 회로구성 및 PD와 OP-Amp를 이용한 수신부 회로를 구성하였다. 실험은 다음처럼 진행되었다. 송 수신부 양 끝단에 컴퓨터를 연결한 다음, 텍스트 전송프로그램을 이용하여 텍스트를 전송하였다. 이때 보드 레이트(baud rate), LED 색깔, 전송거리 등 다양한 변화를 주면서 실험을 진행하였다.

• ETRI Journal
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• 제38권1호
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• pp.9-17
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• 2016

We demonstrate a time- and wavelength-division multiplexed passive optical network system employing a vertical-cavity surface-emitting laser array-based optical line terminal transceiver and a tunable bidirectional optical subassembly-based optical network terminal transceiver. A packet error-free operation is achieved after a 40 km single-mode fiber bidirectional transmission. We also discuss an arrayed waveguide grating, a photo detector array based on complementary metal-oxide-semiconductor photonics technologies, and low-cost key devices for deployment in access networks.