PURPOSES : The tire-pavement interaction noise (TPIN) comprises four sources, among which the tire tread vibration noise (TTVN) and air pumping noise (APN) are known to be the most influential. However, when evaluating TPIN, the noise level is estimated based on the overall noise, because general noise measurement methods cannot separate TTVN and APN. Therefore, this study aims to develop a method to separate TTVN and APN in TPIN for quantitative assessment of pavement noise. METHODS : Based on the results of our literature review and frequency band noise data measured in our study, we identified the dominant frequency ranges for TTVN and APN. Additionally, we evaluated TTVN and APN across various pavement types. RESULTS : TTVN was found to be dominant in frequency bands below 800 Hz, while APN was dominant in frequency bands above 800 Hz. Additionally, regardless of the vehicle type, vehicle speed, or pavement type, APN exhibited higher levels compared to TTVN. This result shows that APN has a more significant impact on TPIN than TTVN. CONCLUSIONS : The separation method of TTVN and APN proposed in this study can be utilized to quantitatively assess the relationship between the primary noise sources in TPIN and the characteristics of pavement texture in future research. Furthermore, it is anticipated that characteristics of low TPIN and optimal texture conditions can be proposed to mitigate TPIN, thus contributing to the development of lownoise pavements.

Recently, though it was developed several services using the context-awareness technology of IoT, there exist also obstacles for high quality service. Specifically it is short the study for uncertainty of context-awareness. This study focused on understanding the effect of frequency interference among several environmental factors for location determination to increase precision of location determination. It was found that frequency interference between devices using 2.4Ghz frequency effect on the location determination precision. It was resulted that frequency interference increase the error of location determination precision. Then, we confirmed that it was required the suitable compensation method corresponding to frequency interference.

The objective of this study was to analyse the antivibration characteristics of gloves by frequency band while operating light-weighted powered hand grinder. A methodology to estimate vibration isolation effectiveness of gloves was proposed on the basis of overall R.M.S. transmissibility characteristics. And overall R.M.S. transmissibilities of L-, M- and H-spectra were compared. Electric hand grinder was tested in the laboratory and attenuation performances of 3 different gloves(full finger antivibration glove, open finger antivibration glove, and cotton glove) were considered. Eight healthy male subjects were employed to polish metal plate with a tool. The results indicate that there was no significant difference among antivibration characteristics by frequency bands while operating light-weighted electric hand grinder.

Inverse synthetic aperture radar(ISAR)를 이용하여 콘크리트의 비파괴 검사시 필요한 적정 주파수 대역폭을 결정하기 위해 주파수 합성을 실시하였다. 콘크리트 시편의 내부를 영상화하기 위한 레이더 신호처리 기법을 이용하여 레이더 주파수 2~3.4 GHz, 3.4~5.8 GHz 대역에서 무근 콘크리트 시편과 내부 공동 또는 철근이 있는 콘크리트 시편을 대상으로 실험하였다. 분해능을 높이기 위해 두 측정 주파수 대역을 합성한 2~5.8 GHz대역에서 신호처리를 하여 영상화 결과를 향상시켰다. 주파수 대역폭 변화에 따른 콘크리트 시편 비파괴 검사 결과의 영향을 분석하였다.

Radio astronomy, on its part, requires 'quiet zones' to be able to receive incoming cosmic signals unaffected by interference to enable astronomers and others learn about universe. The agenda item 1.16 of WRC-2000 contains a number of issues relevant for radio astronomy, but some of them are more important than others. The preparations for WRC-2000 have reached a close-to-final stages, with a number of proposals to this agenda item submitted to the ITU by many countries and groups of countries, like APT, CEPT and CITEL. There is no clear preference to anyone of these proposals since their differences are only minor. However, several points remain to be solved in the APT and CITEL. Fortunately, the preparation went very well, and consensus was reached on allocations above 71 GHz and three resolutions. The radio astronomy has obtained about 100 GHz of new spectrum allocations in bands above 71 GHz. In addition, a new resolution was approved by plenary meeting of WRC-2000. It deals with the consideration by a future WRC of sharing and compatibility issues between passive and active services in adjacent bands particularly with the space services (downlinks) into radio astronomy above 71 GHz. Therefore, in future, there should be a need for studies to be made to determine if and under what conditions sharing is possible, given that modifications were made on the basis of requirements known now and that little was known of requirements and implementation plans for active services in bands above 71 GHz.

We have analyzed the frequency sharing in the range of 71-275 GHz, which was adopted as a main topic of the WARC-2000 at the previous conference WARC-97. Though the technology of the active services has not been fully developed in this frequncy range, the heavy usage of this technology is expected in foreseeable future. To protect the passive services from spurious and out-of-band emissions of active services, realignment of the spectrum between 71 GHz and 275 GHz is strongly required. In addition, some effort should be made to allocate special bands for the radio astronomy service.

본 논문에서는 고주파 특성이 우수한 NEC사의 ne71300-N MESFET를 이용하여 24GHz 대역 국부발진기용 주파수 체배기를 설계 및 제작하였다. 멀티하모닉 로드 풀 시뮬레이션을 통하여 최적의 고조파 소스ㆍ부하 임피던스를 선택하였다. 리플렉터를 이용하여 변환 이득을 개선할 수 있었고, 대역저지필터를 이용하여 기본파와 3차 고조파 성분을 억제하였다. 측정한 결과 0 dBm의 입력신호에 대해 출력주파수인 24Ghz에서의 출력 전력은 -3.776dBm이고, 변환 이득은 0.736 dBm, 41.064 dBc의 높은 고조파 억압 특성을 얻었다.