• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 하계종합학술대회 논문집(1)
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• pp.209-212
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• 2004

This paper has been studied the impact of the distance between the signal source and the antenna under test on the antenna measurements such as gain and pattern (Phase). The concept and principles of the far-field in the antenna measurement are reviewed at first. The analysis on the impact has been focused on the 11 m parabola antenna system which will be used in the ground telemetry station for tracking and receiving the S-band ($2200\~2400MHz$) signal of KSLV-I. Also, the impact of the distance on the tracking performance of the antenna system has been analyzed.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 춘계학술대회논문집
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• pp.1022-1027
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• 2001

In this study, the train-induced vibration was measured at many locations at/around the actual service lines and the data base was constructed using the measurement results. The characteristics of train induced ground vibration was categorized and the empirical ground vibration estimating equations were developed. On the ground area (level grounds, embankments, cut sections), the vibration estimating equations were developed in terms of ground vibration level which was related with the distance from the source. Especially for the cut section areas, the vibration levels were expressed with the vibration receiving point expressed by the ratio of vertical distance to horizontal distance(V/H) from the source. As a result, when V/H is 0.96, the vibration estimating equation gives a minimum vibration level.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 추계학술대회 논문집 학회본부
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• pp.142-145
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• 1995

This paper is to develop a measurement system of the displacement distance using ultrasonic sensors. Two 400KHz ultrasonic sensors are used for realizing the measurement system, such as one sensor transmits the sine wave and the other sensor receives this wave. The displacement is measured by the phase difference between transmitting and receiving signals. A phase defecter transforms phase difference to voltage. Because the output voltage pattern has nonlinear characteristics, the relations of the voltage and the distance are learned by a neural network. As the results of teaming, the efficiency of measurement system is improved. This system can measure the displacement distance at the accuracy of 1 micrometer level.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 G
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• pp.2430-2432
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• 1998

Generally, in the best-known Pulse-type type and Frequency Modulated Continuous Wave(FM/CW)-type RF range measurement systems, the nearest measurable distance between antenna of system and targets is limited to several tens of meters. Moreover, in case of high-speed targets it is more difficult to measure the distance precisely. In this paper we design our own RF(X-band) range(up to 15 meters) measurement system usi code correlation for high- speed targets. It 0 the correlation value between transmitting receiving PN (Pseudo -Noise) codes. So we determine the distance between antenna of s and targets using this correlation value. We fabricated it using MIC techniques and experimental results show that the proposed syste fully qualified for a short range measurement syste

• 유통과학연구
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• 제18권3호
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• pp.99-106
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• 2020

Purpose: The purpose of this study is to investigate the influence of perceived risk and psychological distance on purchase intention when purchasing a gift. It focuses on social distances and temporal distances, and aims to identify the interactions between these psychological distances and perceived risk. Data were collected through experiments. Research design, data and methodology: The experiment was carried out through the design of 2 (perceived risk: high/low) × 2 (social distance: far / near) × 2 (temporal distance: far / near) between-subjects design. Participants were 241 undergraduates from two universities in Chungnam and Gangwon, and randomly assigned to one of eight groups. Results: It was confirmed that there is a difference in purchase intention according to the risk perceived by consumers when purchasing a gift. In particular, the difference in purchase intention based on the risk perceived by the buyer was found to be greater as the social distance between the gift giver and the recipient is shorter. In addition, it was confirmed that the intention to purchase a gift was simultaneously influenced by three factors: social distance, perceived risk, and time remaining to purchase a gift. In other words, when both temporal distance and social distance were short, the difference in purchase intention according to perceived risk was greatest. Conclusions: The purpose of this study was to examine how the relationship between perceived risk and purchase intention when purchasing a gift varies with psychological distance. This study found that the closer the relationship between the gift purchaser and the beneficiary and the shorter the time remaining before the gift purchase, the greater the difference in the willingness to purchase due to the perceptual risk. In practice, the results of this study can be used to establish sales promotion strategies for various gift products. Above all, the closer the relationship between the gift buyer and the person receiving the gift, the more differentially there should be a guarantee program that can reduce or eliminate the risk perceived by the buyer. There is also a need to use step-by-step product recommendation programs that can reduce perceptual risk depending on the time remaining until a particular season, such as graduation or Christmas.

• 한국수산과학회지
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• 제44권4호
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• pp.413-422
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• 2011

An improved split-beam transducer for a 50 kHz fish-sizing echo sounder was developed. The main objective of this study was to minimize the side lobe level in the beam pattern and the distance between acoustic centers for adjacent transducer quadrants in the geometrical arrangement of array elements while maintaining a given number of transducer elements and beam width. To achieve these goals, a 32-element planar array transducer ($6{\times}6$ array with one element in each corner missing) was designed using the Dolph-Chebyshev shading function to suppress side lobes in the array beam pattern and fabricated by arranging the inter-element spacing to be substantially equal to half the wavelength using the transducer element of 0.4 times the wavelength in diameter. The performance characteristics of this split-beam transducer were evaluated in the experimental water tank of $5m{\times}5m{\times}6m$ (length${\times}$height${\times}$width). In this study, the design goal of the beam width and side lobe level for transmitting a beam pattern was initially set at $21^{\circ}$ and -30 dB, respectively. However, the measured beam width at 3 dB was $21^{\circ}$ in both directions with side lobe levels of -24.7 dB in the horizontal plane and -25.6 dB in the vertical plane. The averaged beam width at -3 dB of the receiving beam patterns for four receiving quadrants was $31.4^{\circ}$. The transmitting voltage response was 161.5 dB (re $1{\mu}Pa$/V at 1 m) at 50.23 kHz with a bandwidth of 2.16 kHz, and the averaged receiving sensitivity for four receiving quadrants was -178.13 dB (re 1 V/${\mu}Pa$) at 49.8 kHz with a bandwidth of 2.64 kHz.

• 한국전자통신학회논문지
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• 제17권2호
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• pp.213-218
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• 2022

본 연구에서는 드론을 무선으로 충전할 수 있는 고효율 무선 전력 전송 송, 수신 코일 개발에 대한 기술을 소개한다. 드론 스테이션은 드론의 배터리를 충전하기 위해 배터리를 분리 할 필요 없이 무선으로 배터리를 충전할 수 있는 기능을 지원한다. 드론의 배터리를 최단 시간 내에 충전하기 위해서는 무선 충전 효율이 높아야 한다. 드론 스테이션의 무선 충전 효율을 높이기 위해 고효율 송, 수신 코일 제작 방법과 성능 측정 방법을 제시하였다. 송, 수신 코일은 드론의 비행에 방해가 되지 않도록 드론의 크기와 무게를 고려하여 PCB 기판을 이용해 제작하였다. 송, 수신 코일 사이의 거리가 40mm 이상 떨어진 거리에서 88% 이상의 효율을 구현하였다.

• 제어로봇시스템학회논문지
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• 제21권11호
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• pp.1050-1056
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• 2015

In this paper, we use the characteristics of electromagnetic waves underwater attenuation for estimating linear distance between a transmitting node and receiving node, and research underwater vertical plane attenuation model for constructing the underwater localization system. The underwater localization of 2 dimensional with the plane attenuation model in the horizontal plane (H-plane) was proposed previous research. But for the 3 dimensional underwater localization, the additional vertical plane (E-plane) model should be considered. Because the horizontal plane of omnidirectional antenna has the same attenuation tendency in x-y plane according to the distance, whereas in vertical plane shows an irregular pattern in x-z plane. For that reason, in the vertical plane environment, the attenuation should be changed by the position and inclination. Hence, in this paper the distance and angle between transmitting and receiving node are defined using spherical coordinate system and derive an antenna gain pattern using half power beam width (HPBW). The HPBW is called a term which defines antenna's performance between isotropic and other antennas. This paper derives omnidirectional antenna's maximum gain and attenuation pattern model and define vertical plane's gain pattern model using HPBW. Finally, experimental verifications for the proposed underwater vertical plane's attenuation model was executed.

• 비파괴검사학회지
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• 제11권2호
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• pp.15-21
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• 1991

A wireless acoustic emission (AE) system has been developed for continuous monitoring of rotating structures such as turbine rotors. The cable between preamplifier and signal processing unit of a conventional AE system was replaced by the frequency modulated telemetry. The detected signals were modulated and transmitted as an RF signals by the transmitting module, then received and demodulated by the receiving module. The distance between the transmitting and the receiving antennas could be separated up to 10cm within a reasonable signal-to-noise ratio. The simulated AE signals generated by pencil lead breaks from rotating structures were successfully detected using the developed wireless AE monitoring system.

• 한국음향학회지
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• 제5권4호
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• pp.5-15
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• 1986

This pater is a study on the measurement of solid-borne sound propagation in buildings. The purpose of this paper is to present the data needed for comfortable building enevironment. Solid-Borne sound in apartment building was measured at the source of sound and at many receiving locations in building. Dispersion of the sound level was analyzed to understand noises level at different locations. Graphic method as well as polynomial regression techniques were employed. For this experiment, we made use of the TAPPING MACHINE according to the standard rules of ISO as a impulse exciter, and the measurement was carried out after the building has been all completed. Noticeable noise reductions were observed as the distance from the source to the receiving location increases.