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.

셀룰러 시스템에서의 OFDM(Orthogonal Frequency Division Multiplexing)기술의 사용은 단일 반송파 기술과 비교하였을 때 뛰어난 주파수 효율과 광대역 구현 용이성을 가지고 있으나 차세대 이동통신 시스템과 같은 셀룰러 환경 하에서 사용될 시에는 여러 가지 극복해야 할 문제점을 가지고 있다. 그 중에서 해결해야 할 대표적인 문제점은 셀 간 간섭문제이다. 대표적인 채널 할당 기법은 Siemens의 주파수 할당 기법과 ETRI의 주파수 할당 기법이 있는데 Siemens 기법은 간섭문제가 적지만 시스템 효율이 떨어지고, ETRI 기법은 시스템 효율이 증가하나 간섭문제가 Siemens 기법에 비하여 간섭문제와 시스템 복잡도가 커진다는 단점을 가지고 있다. 이러한 단점을 보완하기 위해 본 연구는 실제 특정 지역에서의 사용자 분포를 고려하여 위 두 기법의 특성을 적절히 혼합한 Dynamic 주파수 할당 기법을 적용하여 동일한 조건 하에서 간섭문제를 최소화하면서도 시스템 효율을 높여 사용자 만족을 최대로 할 수 있도록 하고자 한다. 이를 위해 단말의 수를 랜덤으로 분포시켜 해당 셀 내의 사용자 수의 분포에 따라 가변적인 주파수 할당 기법을 적용하고 이를 모의실험을 통해 확인하도록 한다.

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.

A new algorithm for determining optimal accelerometer locations is proposed by using a frequency-domain Hankel matrix which is much simpler to construct than a time-domain Hankel matrix. The algorithm was examined through simulation studies by comparing the outcomes with those from other available methods. To compare and analyze the results from different methods, a dynamic analysis was carried out under seismic excitation and acceleration data were obtained at the selected optimal sensor locations. Vibrational amplitudes at the selected sensor locations were determined and those of all the other degrees of freedom were determined by using a spline function. MAC index of each method was calculated and compared to look at which method could determine more effective locations of accelerometers. The proposed frequency-domain Hankel matrix could determine reasonable selection of accelerometer locations compared with the others.