• Korean Journal of Optics and Photonics
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• v.12 no.4
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• pp.263-269
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• 2001

The influences of background and environmental noise on coincidence detection are investigated with entangled photons produced by parametric down-conversion process. When the down-converted photons are mixed with thermal light, the coincidence rate did not vary with increasing noise level because the accidental coincidences are discriminated at the short resolving time window. The entangled photon source and the coincidence technique can effectively be used for a noise-free communication channel in the new field of quantum information transmission and processing. ssing.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.1
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• pp.239-243
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• 2012

This paper proposes a electric resistor sensor to measure soil moisture. The soil moisture sensor uses resistance to measure the water content of soil. The main idea is the resistance between the sensor probes can vary according to the water content of soil. Then the resistance difference can be converted to the electrical signal. This sensor is very simple and cheap. In this paper several sensors are connected in serial and composed a sensor network. This sensor network is adopted in IMS(Internet Management System) and demonstrated.

• Convergence Security Journal
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• v.11 no.1
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• pp.19-24
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• 2011

This paper describes a passive SID sensor tag that provide physical security functions based on a sensor interface module. It elementarily consists of a serial I/O interface, control module, and sensor module. In this paper, it show tamper-proof security functions by comparison and encryption with the sensor signal data using the physical resistors. The passive SID sensor tag can be realized by the real time management for the safety, forgery, and so on. The proposed SID tag embedded with a sensor module is expected to find wide physical security applications.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.04a
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• pp.854-857
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• 2012

차량용 Wire Harness 전기 장치가 안전과 편의를 위해 차량에 복잡하게 설치되며 자동차 내 외부에의 정보와 제어신호를 잘못 전달해서 발생하는 돌발 교통사고와 Harness의 가공 잘못으로 정격전류 흐름의 방해로 인한 사고로 부터의 안정성을 검토하는 검사시스템 단계의 최적화를 위함이다. 본 논문은 Wire Harness 검사단계 중 Harness Tester를 통해 전선 부분의 도통검사 및 커넥터 체결시 Harness Tester 에 대한 검사 방법 중 Harness Editor 사용하여 7 개의 파일로 변환하던 것을 XML 파일 시스템으로 바꾸어 검사 함으로써 검사단계에서의 손실을 줄일 수 있다. 또한 모바일 기기와 호환 가능하도록 하여 무선으로 Wire Harness를 Open, Short, Extra, add 테스트 하는 방법을 연구 하였다.

• Proceedings of the KIPE Conference
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• 2018.11a
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• pp.92-94
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• 2018

본 논문은 SiC MOSFET 디바이스를 사용하는 전력변환장치에서 Rogowski 코일을 이용하여 SiC MOSFET 디바이스에 흐르는 전류를 측정하여, 과전류를 검출하고 게이팅 신호를 차단하는 기법에 관하여 연구한다. SiC MOSFET는 소자의 특성으로 보편적으로 사용되는 과전류 검출 방법인 DeSAT 적용이 어렵기 때문에 Rogowski 코일을 사용하여 스위치 전류를 측정, 과전류를 검출한다. 본 논문에서는 PCB패턴 Rogowski 코일의 설계 방법뿐만 아니라 Rogowski 코일과 적분기의 대역폭에 대해서도 논의한다. 실험은 직류링크 커패시터에 SiC MOSFET 스위치 레그를 병렬로 연결하고, 직류링크 커패시터에 직류전압을 충전 후 스위치 레그를 약 6us정도 단락시켜 SiC MOSFET에 과전류를 발생시킨다. 이 때, 제안한 Rogowski 코일을 이용한 과전류 검출 및 차단 기법의 적용 전후를 비교하여 동작 및 성능(검출 및 차단 소요시간)을 확인한다. 마지막으로 실험 결과를 통해 본 논문에서 제안한 PCB패턴 Rogowski 코일을 이용하여 과전류 검출 및 차단 기법이 검증되었다.

• Journal of Biomedical Engineering Research
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• v.23 no.1
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• pp.49-60
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• 2002

Receive dynamic focusing with an array transducer can provide near optimum resolution only in the vicinity of transmit focal depth. A customary method to increase the depth of field is to combine several beams with different focal depths, with an accompanying decrease in the frame rate. In this Paper. we Present a simultaneous multiple transmit focusing method in which chirp signals focused at different depths are transmitted at the same time. These chirp signals are mutually orthogonal in a sense that the autocorrelation function of each signal has a narrow mainlobe width and low sidelobe levels. and the crossorelation function of any Pair of the signals has values smaller than the sidelobe levels of each autocorrelation function. This means that each chirp signal can be separated from the combined received signals and compressed into a short pulse. which is then individually focused on a separate receive beamformer. Next. the individually focused beams are combined to form a frame of image. Theoretically, any two chirp signals defined over two nonoverlapped frequency bands are mutually orthogonal In the present work. however, a tractional overlap of adjacent frequency bands is permitted to design more chirp signals within a given transducer bandwidth. The elevation of the rosscorrelation values due to the frequency overlap could be reduced by alternating the direction of frequency sweep of the adjacent chirp signals We also observe that the Proposed method provides better images when the low frequency chirp is focused at a near Point and the high frequency chirp at a far point along the depth. better lateral resolution is obtained at the far field with reasonable SNR due to the SNR gain in Pulse compression Imaging .

• Journal of the Korean Society for Nondestructive Testing
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• v.33 no.5
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• pp.465-471
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• 2013

A steam generator in nuclear power plant is a heatexchager which is used to convert water into steam from heat produced in a nuclear reactor core, and the steam produced in steam generator is delivered to the turbine to generate electricity. Because of damage to steam generator tubing may impair its ability to adequately perform required safety functions in terms of both structural integrity and leakage integrity, eddy current testing is periodically performed to evaluate the integrity of tubes in steam generator. This assessment is normally performed during a reactor refueling outage. Currently, the eddy current testing for steam generator of nuclear power plant in Korea is performed in accordance with KEPIC & ASME Code requirements, the eddy current testing system is consists of remote data acquisition unit and data analysis program to evaluate the acquired data. The KEPIC & ASME Code require that the electrical properties of remote data acquisition unit, such as total harmonic distortion, input & output impedance, amplifier linearity & stability, phase linearity, bandwidth & demodulation filter response, analog-to-digital conversion, and channel crosstalk shall be measured in accordance with the KEPIC & ASME Code requirements. In this paper, the measurement requirements of electrical properties for eddy current testing instrument described in KEPIC & ASME Code are presented, and the measurement results of newly developed eddy current testing instrument by KHNP(Korea Hydro & Nuclear Power Co., LTD) are presented.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.15 no.10
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• pp.829-841
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• 1990

On assuming that the transmission speed of the original information is the fifth-order transmission speed of the Korea digital multiplex hierarchy (564.992Mb/s), this paper proposes a new structure of the transmission line frame at the terminal repeater system, in order to not only maintain and conserve 565Mb/s optical fiber transmission system but also make the B.S.I. of digital communication network for the optical transmission. And the structure uses the mBIZ transmission line code, which is considered the optimal transmission line code of conventional transmission line codes. System hardware of the transmission line frame structure proposed in this paper is consisted by a method of pulse stuffing after converting the speed of the original information signal sequence at the terminal repeater system for 565Mb/s optical transmission. As a result of this, we can prevent the optical transmission system from a domino phenomenon, the phenomenon of the continuous error multiplication of systems by the transmission error, and suppress timing jitter and the identical consecutive digit number. And also we can improve SNR of the optical transmission system about 2dB because of raising total BER at the optical terminal system up to 10.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.3 no.4
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• pp.255-260
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• 1991

A voltage measuring system specified for the voltage fluctuation of the Pusan-Hamada submarine cable is developed by adding circuits of differential amplification and analog-to-digital conversion to a microprocessor-based data logger with a data modem. This system is charaterized by its small size. no power failure. fully unmanned operation. and precise instrumental drift correction. In addition to the cable voltage and current it measures an ambient temperature and a mercury cell voltage in order to calibrate temperature effect and check its long-term stability. The data acquired by this system show that the voltage signal. comprising fast random noises with a constant width of about 0.2V. fluctuates within a range of about 1V and the fluctuation frequency is similar to that of tidal motion. The source voltage of power feeding equipment (PFE) for the cable system seems to be affected when the room temperature changes rapidly.

• Korean Journal of Food Science and Technology
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• v.19 no.2
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• pp.129-133
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• 1987

To develop a microcomputer-based data acquisition system for measurement of variables such as temperature and weight in food process, a low-cost data acquisition system was developed using an Apple II microcomputer. The system consisted of a microcomputer, a temperature sensor made of pt-100, a strain gauge load cell for weighing, a preamplifier for signal conditionings and an interface device. Interface device was built with programmable interface chip MC 6821, tristate buffer 74244 and analog-to-digital converter ADC 0809. The analog signals of temperature and weight were serially acquisited upon the program. The BASIC language was used for operating the data acquisition and data handling programs. The system successfully measured the variables such as temperature and weight with various sampling intervals in food dehydration process.