남해 중앙부해역의 해양환경특성을 파악하기 위해 표층 퇴적물중의 와편모. 조류 시스트와 유기물 분포에 대한 조사를 2002년 4월부터 2003년 1월가지 총 6회 실시하였다. 분석 항목 중 함수율, 강열감량, 화학적 산소요구량, 입자성 유기탄소, 입자성 유기질소, 식물색소량은 각각 38.7~68.9% 3.9~ 12.5%, 9.60~44.05 m9O2 gdry-1, 3.12~13.14mgC gdry-1, 0.49~

A centralized inventory system provides a number of stores with cost reduction, information sharing. To build centralized warehouses, two things should be considered: how many warehouses are required and where these are located. The number and location of centralized warehouses can be determined in minimizing total costs and then these cost reductions should be allocated fairly to each store. Since it is too time-intensive to find an optimal solution of minimizing total costs, this paper presents heuristics and compares its results with an optimal solution.

Median frequency can be regarded as a valid indicator of local muscle fatigue. As local muscle fatigue develops, the muscle fiber conduction velocity decreases, the fast twitch fibers are recruited less, and consequently the median frequency shifts toward the lower frequency area. The aim of this study was to test the characteristics of the median frequency according to exercise load (30% and 60% of MVC on the biceps brachii, 40% and 80% of MVC on the vastus lateralis) during the fatiguing isometric exercise. Thirteen healthy male volunteer students of Yonsei University were recruited. After the testing maximal voluntary isometric contraction, three variables (initial median frequency, regression slope, fatigue index) from the regression line of MDF data were measured in each exercise load. The results showed that the regression slope and fatigue index were significantly different for the biceps brachii, but not for the vastus lateralis initial MDF was not significant difference according to the exercise load on both muscles. The regression slope and fatigue index could monitor physiologic muscle change during fatiguing isometric exercise. The results showed that two MDF variables reflect the local muscle fatigue according to the exercise load.

본 연구에서는 단부 철근콘크리트와 중앙부 철골로 이루어진 혼합구조보의 비선형 이력거동에 대한 해석 모형을 제시하였다. 해석을 위하여 IDARC2D 프로그램을 사용하였으며, 기존의 실험결과를 대상으로 적절한 모형화 기법과 계수를 제시하였다. IDARC2D의 다각형 모형은 부재의 초기강성을 과대평가할 수 있기 때문에, 먼저 혼합구조보의 초기강성을 적절히 표현할 수 있는 새로운 혼합모형을 도입하였다. 그리고 혼합모형을 이용하여 혼합구조보의 이력거동을 적절히 표현할 수 있도록 이력거동 계수들을 제시하였다. 끝으로 해석한 결과를 실험결과와 비교평가하였으며, 초기강성은 5%이내, 강도는 10%이내의 우수한 결과를 보였다.

19명의 건강한 성인 남자의 우세팔쪽 위팔두갈래근에서 피로가 생길 때까지 2.4초를 하나의 주기로 팔꿉을 반복적 등장성으로 굽히고 펴서 표면근전도 신호를 얻었다. 처리과정 A 중앙주파수(MDF )는 이 신호의 0.5초 구간을 power spectrum analy sis (PSA)로 계산하였는데 상당량의 잡음이 있었다. 중앙주파수의 잡음 양을 비교하기 위해, 동일한 표면근전도에서 3번까지 신호를 받았다 (2.4초 구간을 PSA로 계산한 처리과정 B, 13 point로 moving averages한 처리과정 C, digital low pass filter한 처리과정 D). 그리고 나서 그 신호의 중요 주파수 성분을 뽑아내었다. 위의 중앙주파수 자료와 시간간의 회귀직선을 분석하면 초기 중앙주파수, 회귀기울기, 그리고 피로지수와 같은 모수를 얻을 수 있다. 비모수 검정의 하나인 Kendall 기법으로 네 개의 처리과정간의 모수를 비교하였다. 통계결과 잡음이 처리과정 A보다 B,C,D에서 적었고, D에서 가장 적게 나타났다. 중앙주파수를 digital low pass 로 여과(filtering)함으로써 앞으로 있게 될 동적 운동 시 근피로 모니터기의 신뢰도를 높일 수 있다.

Many studies have shown that the initial median frequency (MDF) and slope correlate with the muscle fiber composition. This study tested the hypothesis that the initial MDF and slope are fixed, regardless of the interval at which data are collected. MDF data using moving fast Fourier transformation of EMG signals, following local fatigue induced by isotonic exercise, were obtained. An inverse FFT was used to eliminate noise, and characteristic decreasing regression lines were obtained. The regression analysis was done in three different periods, the first one third, first half, and full period, looking at variance in the initial MDF, slope, and fatigue index. Data from surface EMG signals during fatiguing isotonic exercise of the biceps brachii and vastus lateralis in 20 normal subjects were collected. The loads tested were 30% and 60% maximum voluntary contraction (MVC) in the biceps brachii and 40% and 80% MVC in the vastus lateralis. The rate was 25 flexions per minute. There were no significant differences in the initial MDF or slope during the early or full periods of the regression, but there was a significant difference in the fatigue index. Therefore, to observe the change in the initial MDF and slope of the MDF regression line during isotonic exercise, this study suggest that only the early interval need to be observed.

Fatigue is the decline in force produced as a result of prolonged muscle activity. Localized muscle fatigue can be identified by a shift toward low in the frequency components of the EMG signal, typically represented by a fall in the median frequency. Previous studies show that a shortened muscle develops a higher fatigue than elongated muscles. The purpose of this study was to investigate the time-related change of median frequency and torque during maximal isometric back extension exercises at different exercise angles (, , , ). Twenty healthy subjects (mean age = ) were evaluated in this study. Median frequency was extracted from the EMG signals by fast Fourier transform (FFT). Initial median frequency and the slope of median frequency change over time were computed from linear regression analysis. Pearson's product moment correlation was used to quantify the relationship between slope of median frequency and torque. The results were as follows: 1) Significant differences in y-intercepts of torque regression equation with respect to exercise angle were shown. However, there were no differences in the slopes of the median frequency and torque, and y intercept of the median frequency among exercise angles. 2) There was no significant correlation between slope of median frequency and torque. 3) But there was moderate correlation between median frequency and torque at each exercise angle. In conclusion, the exercise angle during maximal isometric back extension exercise is not a direct effect on slope of median frequency and torque. But results showed that median frequency and torque shift were highly correlated in all subjects.