• Journal of electromagnetic engineering and science
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• 제18권3호
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• pp.188-198
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• 2018

In this study, we propose an approach for the design and satisfy the requirements of the fabrication of a small, lightweight, reliable, and stable ultra-wideband receiver for millimeter-wave bands and the contents of the approach. In this paper, we designed and fabricated a stable receiver with having low noise figure, flat gain characteristics, and low noise characteristics, suitable for millimeter-wave bands. The method uses the chip-and-wire process for the assembly and operation of a bare MMIC device. In order to compensate for the mismatch between the components used in the receiver, an amplifier, mixer, multiplier, and filter suitable for wideband frequency characteristics were designed and applied to the receiver. To improve the low frequency and narrow bandwidth of existing products, mathematical modeling of the wideband receiver was performed and based on this spurious signals generated from complex local oscillation signals were designed so as not to affect the RF path. In the ultra-wideband receiver, the gain was between 22.2 dB and 28.5 dB at Band A (input frequency, 18-26 GHz) with a flatness of approximately 6.3 dB, while the gain was between 21.9 dB and 26.0 dB at Band B (input frequency, 26-40 GHz) with a flatness of approximately 4.1 dB. The measured value of the noise figure at Band A was 7.92 dB and the maximum value of noise figure, measured at Band B was 8.58 dB. The leakage signal of the local oscillator (LO) was -97.3 dBm and -90 dBm at the 33 GHz and 44 GHz path, respectively. Measurement was made at the 15 GHz IF output of band A (LO, 33 GHz) and the suppression characteristic obtained through the measurement was approximately 30 dBc.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.1
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• pp.277-282
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• 2006

It is well known that Kalman filtering is an optimal real-time data fusion method for GPS/INS integration. However, it has some limitations in terms of stability, adaptability and observability. A Kalman filter can perform optimally only when its dynamic model is correctly defined and the noise statistics for the measurement and process are completely known. It is found that estimated Kalman filter states could be influenced by several factors, including vehicle dynamic variations, filter tuning results, and environment changes, etc., which are difficult to model. Neural networks can map input-output relationships without apriori knowledge about them; hence a proper designed neural network is capable of learning and extracting these complex relationships with enough training. This paper presents a GPS/INS integrated system that combines Kalman filtering and neural network algorithms to improve navigation solutions during GPS outages. An Extended Kalman filter estimates INS measurement errors, plus position, velocity and attitude errors etc. Kalman filter states, and gives precise navigation solutions while GPS signals are available. At the same time, a multi-layer neural network is trained to map the vehicle dynamics with corresponding Kalman filter states, at the same rate of measurement update. After the output of the neural network meets a similarity threshold, it can be used to correct INS measurements when no GPS measurements are available. Selecting suitable inputs and outputs of the neural network is critical for this hybrid method. Detailed analysis unveils that some Kalman filter states are highly correlated with vehicle dynamic variations. The filter states that heavily impact system navigation solutions are selected as the neural network outputs. The principle of this hybrid method and the neural network design are presented. Field test data are processed to evaluate the performance of the proposed method.

• 한국산학기술학회논문지
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• 제10권5호
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• pp.947-954
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• 2009

본 논문에서는 하이브리드 커플러를 이용하여 구성하는 종래의 평형전력증폭기의 입력측 반사전력을 별도의 보조증폭기의 입력으로 활용하여 성능을 개선한 새로운 구조의 평형전력증폭기를 제안한다. 평형증폭기 내의 개별 단일 증폭기의 정합이 완벽하지 못하므로 여기에서 반사된 전력이 하이브리드 커플러의 격리단자에서 터미네이션 시키는 것이 종래의 구성이었다. 본 논문에서는 격리단자에 터미네이션 대신 보조증폭기를 연결하여 누설전력이 입력되고, 보조증폭기의 출력이 최종적인 평형증폭기의 출력에 더해지므로 출력전력과 효율이 개선된다. 제시한 구조를 검증하기 위하여 종래의 평형전력증폭기와 제안된 평형전력증폭기를 실제 제작하고 측정한 결과를 보인다. 제시한 평형전력증폭기는 종래의 평형전력증폭기보다 약 3dB의 출력전력특성, 5.2%의 전력부가효율, 그리고 $5{\sim}10\;dBc$의 IMB3 개선효과를 갖는다.

• 무역상무연구
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• 제38권
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• pp.229-262
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• 2008

With the introduction of supply chain management concept, the nature of a firm is fundamentally changed. Control is no longer based on direct control of the business processes, but rather based on integration across member organizations in the supply chain. Firms are trying to achieve a competitive edge by managing their supply chain performance to gain advantages in cost and service differentiation. The supply chain elements of a sea port involves ILSP (Inbound Logistics Service Provider) at the input side and OLSP (Outbound Logistics Service Provider) at the output side. The goal of sea port is to satisfy the needs of different parties, both upstream and downstream, in the chain with greater effectiveness and efficiency than it's competitors. In this context, the purpose of this paper is to derive conceptualization of the SCP (Supply Chain Performance) in the sea port from literature review on the previous researches and to tackle their theoretical and practical implications. The paper deals with conceptualizing SCP in sea port using the SCOR (Supply Chain Operation Reference) model. It incorporates both the effectiveness and efficiency aspects of performance measurement. And it also recognizes customer related reasons for measuring performance.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.303-310
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• 2011

This paper is focused on development of models for measuring lateral and vertical track irregularities from corresponding accelerometers of an in-service high-speed train. Generally, the track irregularity was measured by a special railway inspection vehicle or system with contact or non-contact sensors. However, the sensors are very expensive and vulnerable to a harsh environment. Displacement estimation from an inertial measurement unit and its wave-band filtering was already developed in the previous study, and it was found that their results included not only the track irregularities but also other information such as phase delay of the applied filters, and suspension and conicity of the wheel. To identify the track irregularities from those results, a compensation filtering method was proposed. Each directional compensation filter was derived by using a system identification method with the estimated directional displacement as input and the corresponding track irregularities as output. In this paper, they are integrated into a model for each direction and applied to the measured lateral and vertical acceleration data from the axle-box and bogie of an in-service high-speed train. Their results are compared with the data from the track geometry measurement system. From the comparison, the proposed models are a useful tool for the measurement of the track irregularities using accelerometers of in-service high-speed trains.

• 대한기계학회논문집B
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• 제29권10호
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• pp.1119-1129
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• 2005

A new measurement system of wall pressure fluctuations on a rotating machinery, composed of digital recording device, was developed and evaluated. The small-sized digital recording device was attached on the rotating machinery and then was detached for data reduction. In order to obtain the system transfer function of the digital recording system, a dynamic calibration was performed utilizing the signal from a 1/8 inch B&K microphone as input. The time history of the unsteady pressure was then reconstructed from the output of the sensor by using this transfer function. The reconstructed pressure signals showed good agreement with the reference signal in both temporal and spectral sense. This sensor was then used to measure the wall pressure fluctuations on a rotating blade. An array of microphones were installed on the blade in the circumferential and radial directions. Various statistical moments were obtained from the measurement data set. Comparison of these quantities with the existing studies demonstrated satisfactory agreement. These tests give credence to the relevance and reliability of this device for applications in more complicated turbulent rotating machineries.

• 한국정밀공학회지
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• 제14권11호
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• pp.126-134
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• 1997

In this study, We made visual inspection system using Vision Board. It is consist of an illuminator (a fluorescent lamp), image input device (CCD (Charge-Coupled Device) camera), image processing system(Vision Board(FARAMVB-02)), image output device (video monitor, printer), and a measuring instrument(TELMN1000). Length measurement by visual inspection system make use of 100mm guage block(instead of calculating distance between a camera and a object). It measured horizontal and vertical length factor from 400mm to 650mm by increasing 50mm. In this place, measured horizontal and vertical length factor made use of length measure- ment of a injection. A measuring instrument used to ompare a measured length of a injection visual inspection system with it. In conclusion, length measurement of a injection compared a measuring instrument with visual inspecion system using length factor of 100mm gauge block. We find that maximum error of length is 0.55mm when it compar with the measuring value of two devices(FARAMVB-02, TELMN1000). Program of visual inspection system is made up Borland C++3.1.

• KIEAE Journal
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• 제7권4호
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• pp.147-152
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• 2007

Numerous non-destructive tests(NDT) to assess the safety of real structures have been developed. System identification(SI) techniques using dynamic responses and behaviors of structural systems become an outstanding issue of researchers. However the conventional SI techniques are identified to be non-practical to the complex and tall buildings, due to limitation of the availability of an accurate data that is magnitude or location of external loads. In most SI approaches, the information on input loading and output responses must be known. In many cases, measuring the input information may take most of the resources, and it is very difficult to accurately measure the input information during actual vibrations of practical importance, e.g., earthquakes, winds, micro seismic tremors, and mechanical vibration. However, the desirability and application potential of SI to real structures could be highly improved if an algorithm is available that can estimate structural parameters based on the response data alone without the input information. Thus a technique to estimate structural properties of building without input measurement data and using limited response is essential in structural health monitoring. In this study, shaking table tests on three-story plane frame steel structures were performed. Out-put only model analysis on the measured data was performed, and the dynamic properties were inverse analyzed using least square method in time domain. In results damage detection was performed in each member level, which was performed at story level in conventional SI techniques of frequency domain.

• 한국산업정보학회논문지
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• 제11권1호
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• pp.49-57
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• 2006

현재 선박의 대형화 및 선박의 운항시간 단축 요구 등의 환경변화에 따라 컨테이너터미널의 생산성 향상이 요구되고 있다. 컨테이너터미널의 생산성은 어떠한 생산성 평가 모델을 이용하여 생산성을 측정하는지와 투입요소인 장치장, 장비, 종업원, 시설 등의 개별적인 투입요소에 따라 서로 다른 측정 결과가 나온다. 그러나 컨테이너터미널의 생산성을 측정하는데 단순히 부분적인 생산성 평가 모델이나 기존의 일반적인 투입 요소만으로 생산성의 정도를 평가하는 것은 문제점을 가지고 있다. 따라서, 본 연구에서는 컨테이너터미널의 생산성을 측정하기 위해, 기존의 컨테이너터미널 생산성 평가 모델에 관한 분석 및 투입과 산출의 명확한 인과관계를 밝히기 어려운 의사결정단위들의 상대적 효율성을 평가하기 위해 개발된 자료포락분석(DEA) 기법을 활용하여 컨테이너터미널의 생산성을 평가하고자 한다. 더불어 투입요소의 변화에 따라 생산성의 측정 결과가 어떻게 변화하는지 파악하여 보다 정확한 생산성 평가 모델을 제시하고자 한다.

• 한국비블리아학회지
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• 제31권1호
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• pp.193-212
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• 2020

우리나라에서 공공도서관의 봉사대상인구는 학술담론이 부재한 채 건립, 리모델링, 서비스 계획의 수립과 평가 등에 적용되고 있다. 이 연구에서는 법률, 지침, 자료 등을 토대로 한 문헌연구와 미국, 호주, 일본과 한국의 사례에 대한 비교분석을 통해 봉사대상인구를 봉사계획인구와 봉사인구로 구분하여 재정의하고 각각의 산출방식을 제안하였다. 봉사계획인구는 건립이나 리모델링에 따른 투입자원을 산출하기 위한 용도로 사용되며, 공공도서관이 서비스 할 수 있는 지역적 범위에 거주하는 인구로 인구통계학적 특성만을 확인할 수 있다. 봉사계획인구의 산출은 계획시점의 행정구역인구를 기초로 인구 10만 이상의 도시지역에는 도서관을 중심으로 반경 2km 이내의 인구와 개관연도까지의 추계인구를 적용하고, 인구 10만 미만의 지역에서는 행정구역의 최소단위인 읍·면·동의 인구와 추계인구로 설정할 것을 제안하였다. 반면, 봉사인구는 개별 공공도서관의 서비스 계획 수립이나 평가, 홍보 등에 사용되며, 실제 공공도서관을 이용하는 이용자이거나 공공도서관의 투입자원에 따라 결정되는 수혜대상 인구로 정의할 수 있다. 봉사인구는 공공도서관의 등록회원 수나 서비스 참가자 수, 투입자원의 규모에 따라 산출한 서비스 수혜대상 수 등으로 산출할 수 있다. 제안된 방식을 적용하면 효율적인 공공도서관의 시설 배치나 자원 투입이 가능하며, 투입 대비 산출에 대한 측정 신뢰도를 제고할 수 있다는 이점이 있다. 더불어 이 연구에서는 봉사대상인구 적용에 따른 혼란을 피할 수 있도록 『도서관법』 제3조 제1항의 <별표1>을 삭제하고, 기준이나 매뉴얼과 같이 개정이 유연한 자료에 개념 및 산출 근거 등을 명시할 것을 제안하였다.