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승용차에 대한 가치 및 평가기준이 차종선택에 미치는 영향
이용학 한국상품학회 2004 商品學硏究 Vol.0 No.31
The main purpose of this study is to examine influences of the value & evaluative criteria about motor-car on the choice of car-types, and to contribute to be devised effective marketing strategies. In order to solve these research problem, a survey was conducted from Nov. 18-22, 2002. 680 female and male adults living in Seoul were abstracted by convenience sampling method. The results are as follows. First, the values about motor-car were classified as five factors. Those are named as "symbolism", "rationalism", "utilitarianism", "eco-friendly", and "instrumentalism". Second, evaluative criteria were classified as five factors. Those are named as "function", "design", "economic", "space", and "corporate image". Third, values were verified to influence on evaluative criteria. Fourth, values and evaluative criteria were verified to influence on the choice of car-types.
Wave Digital Filters의 성능에 관한 연구
이용학,유수현,김재공 한국통신학회 1990 韓國通信學會論文誌 Vol.15 No.6
디지털 필터의 실현시 필터 계수를 유한어장으로 양자화할 때 계수 오차가 나타난다. 이 오차는 디지털 필터의 주파수 응답과 출력 특성을 변화시키고 특히 순환 필터에서는 계수 감도를 민감하게 하는 주요 원인 된다. 본 논문에서는 비교적 계수 오차의 감도가 낮은 WDF(Wave Digital Filter)의 계수 감도 특성에 관하여 검토하였다. 고정 소수점 양자화 방법을 이용하여 주파수 응답을 시뮬레이션한 결과유한 어장이 변화할 때 WDF의 주파수 응답이 기존의 cascade IIR 필터에 비해 비교적 우수함을 보였다. In the implementation of digital filters, the coefficient errors are occurred when filter coefficients are quantized by finite wordlength. They change the frequency responsed and output characteristics of the filters and therefore they become a main reason which could stimulate coefficient sensitivity especially in recursive filters. In this paper, we study the characteristics of coefficient sensitivity for WDF that is less effective to the coefficient errors. The simulation based on the method of fixed-point quantization demonstrates that the frequency responses of WDF have better preformance than those of conventional cascade IIR filter when variations of finite wordlength is considered.
컴퓨터 모의실험을 이용한 Stop-and-wait ARQ 기법 성능 평가
이용학,이호준,최길용,장재신 인제대학교 2012 仁濟論叢 Vol.27 No.1
ARQ schemes are commonly used in various communication areas, for instance TCP protocol, to combat communication packet errors and there are three different types of ARQ protocol. In this paper, the performance of stop-and-wait ARQ scheme is evaluated with computer simulation and then compared with analytical results. Two different traffic generation modes are considered: the first one is the saturated traffic model and the other one is periodic arrival model based on exponential distribution. For performance measures, link utilization and average packet delay are used in this paper. According to numerical results, it is known that performance results from computer simulations coincide well with those by mathematical analysis. For the further study, we will continue to carry performance evaluations of two other ARQ schemes, go-back-N ARQ and selective repeat ARQ schemes.