• Journal of the Korean Institute of Telematics and Electronics
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• v.21 no.3
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• pp.6-12
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• 1984

The basic binary quantized first-order digital phase locked loop (DPLL) is modified in order to reduce the aquisition time and steadyftate phase error. Adding the loop that corrects the phase difference by detecting the falling zero-crossing time, an effort for the improving the performance is performed and the performance compared with that of the basic DPLL. Using a graphical method, the phase locking processes of the modified DPLL for a phase step and a frequency step input are depicted visually in the absence of noise. The performance of the modified DPLL for a sinusoidal input added narrow band random noise is evaluated using the Chapman-Kolmogorov equation. This approach is verified by direct computer simulation. The steady-state phase error and the average aquisition time of the modified DPLL are compared with those of the basic DPLL, It is shown that the aquisition time of the modified DPLL is shortened about twice, also, as signal to noise ratio increases, the effect of the modification increases and the steady-state phase error approaches to zero.

• Proceedings of the KIEE Conference
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• 2001.07a
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• pp.464-466
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• 2001

In this paper, we developed the on-line Data Aquisition System(DAS) of distribution transformers using the hardware and monitoring program. The DAS consists of the top oil temperature sensing part, ambient temperature sensing part, load current sensing part, acoustic emission peak-value sensing part, acoustic emission pulse counter part, micro-processor part and wireless communication part. The Monitoring System consists of the communication setting, online monitoring and database construction part. The DAS send the data acquired from the some sensors of the distribution transformers to the host PC. The monitoring program of the host PC stores the data to database. And the monitoring system estimates the loss of life time for distribution transformer from the DB. Thus, it could be managed the career and the functional lifetime of the transformer more efficiently than existing methodologies.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.841-848
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• 2008

This paper examined dynamic characteristics of high speed trains using a time varying frequency transform. Fourier transform based methods are frequently used for the calculation of the dynamic characteristics of trains in the frequency domain, but they cannot represent the time-varying characteristics. Therefore it is necessary to examine their characteristics using a time-varying frequency transform. For the examination, the non-stationary vibration of wheelset, bogie, and carbody are measured using accelerometers and stored in a data aquisition system. They are processed with localization of the data by modulating with a window function, and Fourier transform is taken to each localized data, called the short-time Fourier transform. From the processed results, time varying auto-spectral density, cross-spectral density, frequency response, and coherence functions have been calculated. From the analysis, it is confirmed that the time varying frequency transform is a useful method for analyzing the dynamic characteristics of high speed trains.

• Proceedings of the IEEK Conference
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• 2003.07b
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• pp.1201-1204
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• 2003

This paper described a replica-delay adaptive lock-acquisition scheme for high-speed DLLs. The proposed scheme provides the fast and correct locking cycle that is variable according to the magnitude of the arbitrary replica delay (fixed delay). The scheme guarantees the wide operation range and the fast lock-aquisition time. It has been confirmed by HSPICE simulations in a 0.35${\mu}{\textrm}{m}$ CMOS process.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1992.04a
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• pp.256-261
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• 1992

Acquisition of 3D points is an essential process for modelling of physical 3D objects. Although Coordinate Measuring Machine(CMM) is most accurate for this purpose, it is very time consuming. To enhance the data aquisition speed for scuptured surfaces, active vision with reflecctometric method was used for our system. A fter the data acquisition, the system automatically generates cutting tool path for the 3-axis milling of the object. The fullyintegrated system from the data acquisition to the NC-code generation was implemented with IBN-PC/386 and necessary hardwears.

• Publications of The Korean Astronomical Society
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• v.4 no.1
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• pp.53-62
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• 1989

낱별의 광전측광 관측을 위하여 두 가지 컴퓨터 프로그램을 개발하였다. 하나는 자료수집 (data aquisition), 자료의 표시, 통계처리, 오차추정, 대기상태의 모니터링 등을 다루는 실시간(實時間, real time) 측광제어 프로그램이고, 다른 하나는 하룻밤 관측의 도중 또는 관측 종료 직후에 수집된 자료 전체를 입력 파일로 만들어 주면 대기소광계수 결정과 표준계 변환 및 오차 추정을 해 주는 자료분석(資料分析, data reduction) 프로그램이다. 두 프로그램은 모두 임의의 다색측광계(多色測光系)에 대해서 입력 과일에 필터의 갯수, 색지 수의 정의 등 필요한 자료만 써주면 수행 가능하도록 일반화되어 있다.

• Proceedings of the Optical Society of Korea Conference
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• 2008.07a
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• pp.273-274
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• 2008

We present a quantitative phase microscopy for live cells. This method uses the principles of common path inteferometry and single shot phase image. This system has the ability to measure live cells quantitatively with subnanometer path length stability and millisecond scale aquisition time.

• IE interfaces
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• v.15 no.4
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• pp.374-381
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• 2002

In this paper, we design and implement a real-time route guidance system(RGS) in large-scale networks. Coupled with the well-known mathematical routing algorithms, we devise an RGS for knowledge aquisition and self-learning ability within the framework of the expert system. Through off-line construction of database, on-line treatment of unexpected traffic accidents, etc., the developed RGS can provide drivers with good quality real-time routing information. The practical effectiveness of the proposed system is demonstrated in terms of response time and route appropriateness.

• Proceedings of the KSRS Conference
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• 2002.10a
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• pp.664-669
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• 2002

Intertidal zone (tidal flat) is a place which is sometimes dry and sometimes wet depending on the tidal rhythm. Direct measurement of topography in the intertidal zone is very difficult to be achieved. The interface between wet and dry parts in the tidal flat, which can be identified from near infrared band of satellite image, is a 'depth contour' which corresponds to the sea level at the time of satellite pass. Aquisition of topography data in tidal flat is possible by combining various techniques such as (1) identification of the interface between wet and dry parts, (2) GCP correction of satellite image, and (3) realtime prediction of sea level elevation at the time of satellite pass. The algorithm was successfully applied in obtaining topography (bathymetry) data in the intertidal zone of Asan Bay in the west coast of Korea from 26 satellite images. The method is expected to be very efficient in making bathymetry data base in the western and southern parts of Korea where tidal flats are well developed in wide regions.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.03a
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• pp.673-678
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• 2002

Laboratory calibration chamber tests for cone penetrometers, pressuremeters and dilatometers in cohesionless soil specimens have been conducted by numerous researchers. However, there have been only few applications to compacted or preconsolidated cohesive soils. Therefore, for the first time, Calibration Chamber System was developed in Korea University. This can be attributed to the extremely time consuming and laborious process involved in the preparation of large cohesive soil specimens in addition to other complexities involving instrumentation for pore pressure monitoring and the need for maintaing saturation by back pressure. Chamber System with similar principle as LSU Chamber System was made of more strengthen and complementary form by increasing system diameter(1.2m), carrying out 1st and 2nd consolidation process in one system for smooth and safe work, accurate Data Aquisition.