• 한국항행학회논문지
• /
• 제28권1호
• /
• pp.116-122
• /
• 2024

본 논문에서는 ILS (instrument landing system) 로컬라이저 전력증폭기의 변조도, 출력, 그리고 위상 변화량 규격의 요구성능을 도출하기 위하여, 시스템의 주요 성능 중에서 course structure와 course width를 연구하였다. Course structure의 편차 규격(± 5 uA)을 만족하기 위한 CSB (carrier with sideband) 증폭기의 변조신호 DDM (difference in depth of modulation) 편차 규격을 ± 1 uA(0.001 DDM)로 규격화하였다. CSB 30 W 전력증폭기를 설계하였고, 변조도 보상회로를 통하여 동작운용 출력범위(45 dBm ~ 35 dBm)에서 SDM (sum in depth of modulation)은 40% ± 0.1%, DDM은 ± 0.0005 DDM의 특성을 얻었다. 그리고 course width와 displacement sensitivity 규격에 대하여 시뮬레이션으로 분석하고, 가장 엄격한 규격인 운용개시 점검시에 적용되는 ± 0.1 ° 변화량을 적용하여, SBO (suppressed with sideband only) 증폭기의 출력변동은 ± 2 mW, 위상은 ± 3 ° 로 규격화하고 특성을 만족하였다. 출력과 온도에 따른 보상회로를 적용하여, 안정적인 변조지수, 출력, 그리고 위상 특성을 얻었다.

• 한국토양비료학회지
• /
• 제48권6호
• /
• pp.593-601
• /
• 2015

The NDVI (Normalized difference vegetation index) is used as indicators of crop growth situation in remote sensing. To measure or validate the NDVI, reliable NDVI sensors have been needed. We tested new fixed-field NDVI sensor, "SRS (Spectral Reflectance Sensor)" developed by Decagon Devices, during Kimchi cabbage growing season at the cultivation area located in Gochang, Gangneung and Taebaek in Korea from 2014 to 2015. The diurnal variation of NDVI measured by SRS (SRS NDVI) showed a slight ${\cap}$-profile shape and was affected by water on the sensor surface. This means that SRS NDVI around noontime is resonable, except rainy day. Comparisons were made between the SRS NDVI and NDVI of used widely mobile sensor (Cropcircle NDVI). The comparisons indicate that SRS NDVI are close to Cropcircle NDVI (R=0.99). SRS NDVI time series displayed change of the plant height and leaf width of Kimchi cabbage. An obvious exponential relationship is found between SRS NDVI and the plant height ($R^2{\geq}0.92$) and leaf width ($R^2{\geq}0.92$) of Kimchi cabbage. Thus, SRS NDVI will be used as indicator of crop growth situation and a very powerful tool for evaluation of remote sensing NDVI estimates and associated corrections.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
• /
• pp.685-692
• /
• 2011

DC/DC switching power converters produce DC output voltages from different DC input sources. The converters can be used in regenerative braking of DC motors to return energy back in the supply, resulting in energy savings for the systems containing frequent stops. The current mode DC/DC converter is composed of a PWM (pulse width modulation) controller, a MOSFET, and inductor, etc. Pulse width modulation is applied to control and regulate the total output voltage. It is shown that the variation of threshold voltage at MOSFET and the offset voltage increase caused by radiation effects make the PWM pulse unstable. In the PWM operation, the missing pulses, the changes in pulse width, and a change in the period of the output waveform are studied by simulation program with integrated circuit emphasis (SPICE) and experiments.

• 제어로봇시스템학회논문지
• /
• 제18권4호
• /
• pp.371-374
• /
• 2012

DC/DC switching power converters produce DC output voltages from different stable DC input sources regulated by a bi-polar transistor. The converters can be used in regenerative braking of DC motors to return energy back in the supply, resulting in energy savings for the systems containing frequent stops. The voltage mode DC/DC converter is composed of a PWM (Pulse Width Modulation) controller, a MOSFET (Metal Oxide Semiconductor Field Effect Transistor), an inductor, and capacitors, etc. PWM is applied to control and regulate the total output voltage. It is shown that the output of DC/DC converter depends on the variation of threshold voltage at MOSFET and the variation of pulse width. In the PWM operation, the missing pulses, the changes in pulse width, and a change in the period of the output waveform are studied by SPICE (Simulation Program with Integrated Circuit Emphasis) and experiments.

• 치과방사선
• /
• 제13권1호
• /
• pp.87-96
• /
• 1983

Radiographic measurements on the width of mandibular cortical plate and the lamina dura and on the root length were done in 42 patients who were in long-term Dilantin medication. Osteoporosis and root abnormalities were also investigated. The obtained results were as follows: 1. The number of male patients was greater than that of female patients. 2. The width of mandibular cortical plate was thinner in patient group than in control group. 3. There was no significant change in the width of lamina dura between the patient group and control group. 4. The root length of patient group was generally shorter than that of control group. 5. There were evidences of generalized mandibular osteoporosis and alteration in mandibular canal wall in 8 patients. (19%) 6. In Dilantin induced osteomalacia, the radiographic changes of mandibular canal wall and mandibular cortical plate were prominent, but that of lamina dura was not significant.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
• /
• pp.193-196
• /
• 2005

This study deals with the estimation of the crack width by stabilized cracking considering bond-slip relationships in reinforced concrete members. The proposed method utilizes the sameness of tension stiffening and a change of bond-slip relationships because of concrete's splitting. The validity, accuracy and efficiency of the proposed method are established by comparing the analytical results with the experimental date and the major code spcifications. The analytical results of analysis presented in this study indicate that the proposed method can be effectively estimated the crack width of the reinforced concrete members.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2006년도 춘계학술발표회 논문집(I)
• /
• pp.210-213
• /
• 2006

The objectives of this study is to find out the relationship of crack width and residual seismic capacity of Unreinforced Masonry(URM) walls which were damaged by earthquake. Three URM walls which made the shape ratio(1/h, 1.0, 1.5, 2.0)to be a variable were tested for the objective. It was seen that the crack width increased with growing at rotation angle. Also, this study found out that failure mode affects crack type of URM. In other words, horizontal and vertical crack was increased in rocking and sliding failure mode respectively.

• 한국강구조학회 논문집
• /
• 제8권4호통권29호
• /
• pp.19-29
• /
• 1996

In this paper, it is presumed that the stress time history was generated by simulation method and investigated compatibility in regard to the reappearance of stress time history. In this procedure, the identified frequency distribution of stress range of the steel railroad bridge varies with the rational values of cut off point and bar width. Thus, we show variable aspect of the equivalent stress range results from change of cut off point and bar width. In addition, we analyze the variable of RMC and RMS model due to the cut off point and bar width of the measured stress history which influencs the prediction of fatigue life in the steel railroad bridge. The simulated stress time history is carried out by the superposition method incorporating the vertical load with rotation moment obtained from the Hermition interpolation function, and compared with developing stress results from measured maxi mum stress. Through this study, we can estimate the remaining fatigue life from a safety point of view and comparative accuracy.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
• /
• 제53권8호
• /
• pp.463-468
• /
• 2004

This paper was applied space harmonic method as a characteristic analysis technique for slotless PMLSM. There is advantages of active response to the change of design parameters as well as reduction of the calculation time. The method can be overcome disadvantages of finite element analysis that needs long times calculation, repetitions of pre and post-process. In this paper, 3D-space harmonic method was applied to consider the precise description of end turn coil shape and the changes of characteristic according to changes of length of z-axis direction. The thrust of optimal design was performed using genetic algorithm to enhance the thrust which is the disadvantage of slotless type PMLSM. For design parameters, width of permanent magnet, width of coil, width of coil inner and lengths of z-axis direction were selected. For objective functions. thrust per weight. thrust per volume. multi-objective function was selected.

• Current Optics and Photonics
• /
• 제6권2호
• /
• pp.191-195
• /
• 2022

We investigate the lateral far-field pattern characteristics, including divergence angle change and far-field pattern analysis as output power increases, of narrow-emitter-width 850 nm GaAs/AlGaAs laser diodes (LDs). Each LD has a cavity of 1200 and 1500 ㎛ and narrow emitter width of 2.4 ㎛ for the top and 4.6 ㎛ for the bottom. The threshold currents are 35 and 40 mA, and L-I kinks appear at power levels of 326 and 403 mW, respectively. The divergence angle tends to increase due to the occurrence of first-order lateral mode and the thermal lensing effect. But with the L-I kink, the divergence angle decreases and the far-field pattern becomes asymmetric. This is due to coherent superposition between the fundamental and the first-order lateral mode. We provide detailed explanations for these observations based on high-power laser diode simulation results.