• Journal of Advanced Marine Engineering and Technology
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• 제33권6호
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• pp.925-931
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• 2009

This paper reports a preliminary experimental investigation and characterization of an optical fiber-based submersion sensor system for applications in water flooding and leakage. The sensor system comprises a multi-mode fiber spliced with fiber Bragg grating and an intensity-based interrogator. Submersion tests were conducted in water-air and Glycerin-air environments. By the refractive index of the fiber-probe surrounding materials, the reflectance and the detecting power level is determined. When the probe is dipped into the water, the optical output power dramatically decreases from -7.5dBm to -17.5dBm. But, the center of Bragg wavelength is not affected in spite of external material changes. Temporal response characteristics of the sensor system is investigated to verify the real-time reaction. When the probe is immersed into the liquid, there is no transition time.

• 전력전자학회논문지
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• 제24권1호
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• pp.33-39
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• 2019

We propose a mechanical parameter estimation algorithm for surface-mounted permanent magnet synchronous motors (SPMSMs) using a sliding-mode observer (SMO) and an adaptive filter. The SMO estimates system disturbances in real time, which contain the information on mechanical parameters. A desirable feature that distinguishes the proposed estimation algorithm from other existing mechanical parameter estimators is that the adaptive filter estimates electromagnetic torque to improve the estimation performance. Moreover, the SMO acts as a low-pass filter to suppress the chattering effect, which enables the smooth output signals of the SMO. We verify the mechanical parameter estimation performance for SPMSM by conducting extensive experiments for the proposed algorithm.

• 전자공학회논문지B
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• 제33B권4호
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• pp.52-62
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• 1996

In this paper, a new continuous-time current-mode integrator as basic building block of the low-voltage analog current-mode active filters was proposed. Compared to the current-mode integrator which was proposed by Zele, the proposed current-mode integrator had higher unity gain frequency and output impedance in addition to lower power dissipation. And also, a current-mode third-order lowpass active filter was designed with the proposed current-mode integrator. The designed circuits were fabricated using the ORBIT's 1.2.mu.m double-poly double-metal CMOS n-well process. The experimental resutls of the active filter designed and fabricated for this research have shown that it has the performance of 44.5MHz cutoff frequency, 3.3mW power dissipation and the third-order active filter area was 0.12mm$^{2}$.

• 항공우주시스템공학회지
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• 제2권3호
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• pp.33-39
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• 2008

VDL Mode 2 is one of air-to-ground VHF digital data link technologies. The VDL Mode 2 system is designed to be an air-to-ground subnetwork of the Aeronautical Telecommunication Network (ATN) using the AM(R)S band and it is organized according to the Open System Interconnection (OSI) model (defined by ISO). It can be used in ATS Applications especially for ATC communication such as CPDLC and ADS as well. And It is expected VDL Mode 2 replaces ACARS(Aircraft Communications Addressing and Reporting System) which has broadly been used for over 20 years. This paper presents the result of design of operational test equipments for the validation of VDL Mode 2 system under development in KARI.

• 전력전자학회논문지
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• 제21권1호
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• pp.27-33
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• 2016

A pulse-width modulation (PWM) method for common mode noise reduction in a PWM inverter connected to a single-phase grid is proposed in this study. The extensively used conventional switching method may experience common mode voltage problems, which generate current leakage and electromagnetic induction problems. In the proposed switching method, the neutral point of the output voltage is always fixed at both ends of the input voltage to reduce common mode noise. The validity of the proposed method is proven through simulation and experimental results.

• 대한기계학회논문집A
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• 제33권11호
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• pp.1239-1243
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• 2009

To evaluate the structural integrity of the nuclear seismic category penetration cooling water pump under the seismic service conditions the seismic analysis was performed in accordance with IEEE-STD-344 code. The finite element computer program, ANSYS, Version 10.0, is used to perform both a mode frequency analysis and an equivalent static seismic analysis of the pump assembly. The mode frequency analysis results show the fundamental natural frequency is greater than 33 Hz and does not exist in seismic range, thus justifying the use of the static analysis. The stresses resulted from various loadings and their combinations are within the allowable limits specified in the above mentioned IEEE code. The results of the seismic evaluation fully satisfied the structural acceptance criteria of the IEEE code. Accordingly the structural integrity on the pump assembly was proved.

• 한국항공우주학회지
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• 제33권5호
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• pp.57-64
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• 2005

현대의 고성능 전투기에 탑재되어 있는 전기식 비행제어계통(Digital Fly-By-Wire Flight Control System)은 통합 다기능 감지기(IMFP : Integrated Multi-Function Probe)에 의해 항공기의 고도/속도/받음각 정보를 얻는다. T-50에 적용되어 있는 3개의 IMFP는 3중 결함 및 분리되지 않는 2중 결함에 대해서 비행 안정성(Flight Stability)을 확보하기 위해 형상 재구성 모드(Air Data Reconfiguration Mode)를 제어법칙에 적용했다. 본 논문에서는 항공기 운용 시 발생할 수 있는 IMFP 결함으로 인한 형상 재구성 모드 제어법칙에 대해, 비행 안정성을 해석하기 위하여 선형해석(Linear Analysis) 및 HQS( Handling Quality Simulator) 조종사 시뮬레이션을 수행하였고, T-50 비행시험 시, 발생했던 IMFP 결함으로 인해 제어법칙이 형상 재구성 모드로 적용되었던 사례를 제시했다. 그 결과, T-50 훈련기의 제어법칙이 형상 재구성 모드로 전환될 경우, 항공기 안정성에는 영향이 없다는 것을 알았다.

• 대한원격탐사학회지
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• 제33권4호
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• pp.351-358
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• 2017

A new method to decompose the footprints of marine atmosphere boundary layer (MABL) on Synthetic Aperture Radar (SAR) imagery into characteristic spatial scales is proposed. Using two-dimensional Empirical Mode Decomposition (EMD) we obtain three Intrinsic Mode Functions (IMFs), which mainly present longitudinal rolls, three-dimensional cells and atmospheric gravity waves (AGW). The rolls and cells have spatial scales between 3.0 km and 3.8 km and between 5.3 km and 7.1 km, respectively. Based on previous observations and mixed-layer similarity theory, we estimated MABL's depths that vary from 0.95 km to 1.2 km over the rolls and from 3.0 km to 3.8 km over the cells. The AGW has maximum spectrum at 14.3 km wavelength. The method developed in this work can be used to decompose other satellite imageries into individual features through characteristic spatial scales.

• 한국응급구조학회지
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• 제27권3호
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• pp.33-46
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• 2023

Purpose: This study aims to evaluate the risk of work-related musculoskeletal disorders (WMSDs) in 119 EMT during patient-carrying tasks using a long backboard (LBB) and a variable stretcher. Methods: Manikins were used as patients, and 45 new 119 EMT from K Fire Academy were filmed performing patient-carrying tasks on stairs. The tasks were analyzed using Ovako working posture analysis system (OWAS) and Rapid entire body assessment (REBA). Results: In using LBB, the OWAS score was Mode 3(Mean 2.37, Maximum 3), requiring as soon as possible corrective action, the REBA score was Mode 11(Mean 9.16, Maximum 11), requiring immediate improvement. In using variable stretcher, the OWAS score was Mode 1(Mean 2.33, Maximum 3), non-necessity for corrective action, the REBA score was Mode 9(Mean 8.0, Maximum 11), requiring as soon as possible. Conclusion: In conclusion, improvement was needed in one task (carrying a patient using a LBB) in the OWAS and in two tasks (carrying a patient using a LBB, carrying a patient using a variable stretcher) in the REBA. Thereby, required attention and management of WMSDs during training. In addition, it is essential to carry out objective and quantitative assessments through ergonomic analysis by occupational health professionals when designing future training programs to prevent WMSDs.

• 방송공학회논문지
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• 제21권3호
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• pp.341-348
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• 2016

HEVC 표준은 기존의 H.264 표준을 대체할 차세대 고효율 영상 압축 코덱이다. H.264 표준에 비해 약 50% 수준으로 비트레이트를 감소시켰지만 계산 복잡도는 약 1.4배 정도 증가하였다. 계산 복잡도를 낮추기 위해 다양한 고속화 알고리즘들이 제안되어 왔다. 인트라 코딩에는 rough mode decision(RMD) 기법이 적용되었다. 최적의 모드를 선정하기 위한 rate-distortion optimization (RDO) 과정은 복잡도가 높기 때문에 RMD를 사용하여 더 간소화된 방법으로 RDO 단계를 위한 후보 모드들을 선정한다. 그러나 큰 사이즈의 블록들의 경우 RMD 과정 역시 계산 복잡도를 줄일 필요가 있다. 본 논문에서는 RMD 과정에서 참조 픽셀을 가져오고, 예측 픽셀 생성하는 과정에서 다운 샘플링을 적용하였으며 참조 소프트웨어에 적용된 기존 RMD 방식에 비해 계산량을 70%가량 줄일 수 있었다. 이때 BDBR 증가는 0.04%로 미미한 수준이다. 제안한 다운샘플링 기법을 RMD 하드웨어에 적용하면 게이트 카운트는 약 33%, 버퍼의 크기는 약 66% 줄어든다.