• 대한기계학회논문집
• /
• 제18권4호
• /
• pp.1057-1063
• /
• 1994

An instantaneous frequency analysis is a technique to examine a signature for the rotating machinery if the signal has several transitions within a cycle. This paper discusses the conditions of existing negative frequency components in the instantaneous frequency. By using a signal consisted of two frequency components, the instantaneous frequency analysis is conducted while the amplitude ratio between two frequency components has been changed. The analysis shows that, depending on the amplitude ratio, the instantaneous frequencies have averaged, zero-valued, or negative components. It turns out that the negative-valued instantaneous frequencies, which have been regarded as the noise effect, are the consequence of the calculation process for the multisignal components. The criteria of existing the negative values in instantaneous frequencies is given in terms of the relative amplitude ratio and the frequency difference. Especially when the amplitude ratio approaches to 1, the instantaneous frequency fluctuates ${\pm}\infty$ in theory, which implies that instantaneous frequency has unstable region around the amplitude ratio, 1.Also, as the frequency difference between major signal components is increased, the region of existing negative instantaneous becomes broader. In an instantaneous frequency analysis, therefore, a narrow band analysis is suggested, with extreme care if the amplitude ratio approaches to 1. In this paper, a vibration signal monitored from a rotating machinery is also examined as an application example in order to show the existence of negative instantaneous frequencies components.

• 한국농공학회논문집
• /
• 제62권4호
• /
• pp.45-51
• /
• 2020

The poisson's ratio was obtained from the effective vertical stress and horizontal stress of consolidation-undrained test. It was analyzed void ratio verse poisson's ratio. At the result, the effective friction angle was increase with relative density increased, was decreased the poisson's ratio. The empirical equation of void ratio and poisson's ratio was showed very high correlation r²=0.846. The empirical equation was showed that the smaller the void ratio in the fine grained soil than granular soil. In the case of 0.85 times the correlation analysis equation of granular and fine grained soil, the experimental results were shown very similarly. In especially, the poisson's ratio prediction results was shown within 5% of the error range, was revalidation 0.85 times the correlation analysis equation using the void ratio. In this study, correlation analysis equation of the granular and fine grained soil was more reliability of the poisson's ratio prediction results apply to the void ratio than dry unit weight.

• 대한한의진단학회지
• /
• 제10권2호
• /
• pp.132-150
• /
• 2006

Objectives : The objective is that we measure and analyze Pulse-Respiration Ratio and Body Composition Analysis to study the correlation between both. Methods : First, after subjects take a rest over 10 minutes, we measure their electrocardiogram and respiration pattern through which we take average peak interval to calculate an average pulse cycle and a respiration cycle. An average respiration cycle divided by an average Pulse Rate gives Pulse-Respiration Ratio. Next, we draw out 22 Body Composition Analysis indicators by using In-Body 720 model. Last, we analyze and take statistics on them by using SPSS 13.0 program. Results : Negative is the correlation between P/R Ratio and Body Composition Analysis indicator like fatness degree, body fat volume, body fat rate, abdominal fatness, BMI. Conclusions : 1. The higher P/R Ratio the more likely to be thin, the lower P/R Ratio the more likely to be fat. 2. We separately analyze P/R Ratio depending on each breathing frequency and pulse frequency to find out that breathing frequency has great influence and that breathing frequency decides the fatness degree. 3. In study on the correlation between P/R Ratio and Body Composition Analysis, fatness degree, in-body fat volume, in-body fat rate, BMI are the related indicators, which shows the connection with the fatness indicators. 4. In study on the correlation between Han-Yeol [寒熱] grade and Body Composition Analysis indicators, the result is that Han[寒] has no connection and that only Yeol[熱] grade has something to do with it, which means the higher heat symptom subjects have, the more basic metabolism volume and muscular build they have.

• 산업경영시스템학회지
• /
• 제33권1호
• /
• pp.10-16
• /
• 2010

Mail centers are essential postal facilities that sort and dispatch postal items, and should be operated efficiently to provide customers high quality postal services. So the efficiency analysis of mail centers should be performed in order to induce better operation. But current performance evaluation system has 95 percent of predetermined and weighted non-quantitative indices. There is need to introduce objective efficiency measurement methodology. The main objectives of this study was to analyze the efficiency of 24 mail centers empirically using cone-ratio DEA and suggest the appropriate cone-ratio method. Consequently, this paper suggests that the cone-ratio DEA model integrating decision-maker's preferences is more desirable for efficiency analysis than that of using transformed data.

• 한국콘텐츠학회논문지
• /
• 제8권7호
• /
• pp.224-232
• /
• 2008

프로스포츠 가운데 프로축구는 1983년 출범한 이후 2008년 4월말 현재 14개 구단이 있으며, 구단 형태를 살펴보면 도민구단 1, 시민구단 3, 군 운영 1, 나머지 9개 구단은 모기업의 지원형태로 운영되고 있다. 본 연구의 목적은 4개 시민구단의 실제 재무제표 자료에 기초하여 재무비율 분석을 실시함으로써 실제 시민구단의 형태로 운영되고 있는 프로구단들의 경영상태의 양부(건전성)를 파악하는데 있다. 본 연구결과를 살펴보면 다음과 같다. 첫째, 유동성 비율 측면에서 연도별 추이는 계속 감소 추세를 보이고 있으나 4개 시민구단의 비율평균과 표준비율을 비교하여 판단해 볼 때 양호한 수준이다. 둘째, 레버리지 비율 측면에서 볼 때 일부 시민구단의 경우 부채가 총자본을 초과하는 등 타인자본 의존도가 높아 자본구조의 불안정성을 보이고 있다. 셋째, 활동성 비율은 표준비율과 비교하여 볼 때 4개 시민구단의 각 년도 활동성 비율은 양호한 것으로 나타났다. 마지막으로 수익성 비율은 인천 유나이티드를 제외한 나머지 구단들이 큰 마이너스를 기록하여 수익성이 매우 저조한 것으로 나타났다. 따라서 타인자본 의존도를 줄이고, 수익성 개선을 위한 노력이 요구된다. 본 연구는 새로이 창단 발표를 한 프로축구 강원 도민구단(가칭 강원 FC)에게 유용한 기초 자료로 활용될 수 있을 것이다.

• 대한한의진단학회지
• /
• 제10권2호
• /
• pp.104-120
• /
• 2006

Background : Pulse-respiration ratio has been used for estimating subject's status in oriental medicine. Pulse and respiration is strongly associated with autonomic nerve system. But there is no research about correlation between pulse-respiration ratio and autonomic nerve system. Objectives : We performed this study to know correlation between pulse-respiration ratio and HRV(heart rate variability) that shows autonomic nerve system status well and to clarify clinical meaning of pulse-respiration ratio. Methods : After subject's 10 minutes rest, we measured subject's ECG, respiration pattern and HRV. In this research, subject's number is 95(Male 50/Female 45). We calculated pulse-respiration ratio from ECG and respiration pattern. Then, we analyzed correlation between pulse-respiration ratio and HRV parameters in all subjects, 2 group divided by Wan-Maek(P-R ratio 4.28). We tried to compare HRV parameters among Wan-Maek, Sak-Maek and Ji-Maek group. Correlation analysis between pulse-respiration Ratio and Pulse rate, respiration rate is performed. Finally correlation analysis between Respiration and HRV parameters in all subjects, 2 group divided by Wan-Maek(4.28) is studied. Results : 1. Mean pulse-respiration is 4.10${\pm}$0.67, Mean pulse rate is 68.06${\pm}$7.82bpm, Mean respiration rate is 16.81${\pm}$2.72 times per minute in all subjects. 2. Correlation analysis between pulse-respiration ratio and HRV parameters of high pulse-respiration ratio group is not significant. But, in low pulse-respiration ratio group, HFnorm(correlation coefficient 0.306, p= 0.018), lnHF (0.308, p=0.002) is significantly correlated with pulse-respiration ratio. 3. Comparison of HRV parameters among Wan-Maek, Sak-Maek and Ji-Maek Group is not significant. 4. Pulse-respiration ratio is more affected by respiration rate(correlation coefficient-0.17, p=0.000) than pulse rate (correlation coefficient 0.396, p=0.000). 5. Correlation analysis between respiration rate and HRV parameters of high pulse-respiration ratio group is not significant. But, in low pulse-respiration ratio group, HFnorm (correlation coefficient -0.327, p=0.011), LF/HF(0.346, p=0.007), lnHF (-0.355, p=0.006) are significantly correlated with respiration rate. Conclusion : Pulse-respiration ratio and parasympathetic index has positive correlation. The closer Wan-Maek, The higher parasympathetic index in low pulse-respiration ratio group. Respiration rate is more related with pulse-respiration ratio than pulse rate. Respiration is negatively correlated with autonomic parameters. And the slower respiration, the higher parasympathetic index in low pulse-respiration ratio group.

• Korean Journal of Radiology
• /
• 제23권8호
• /
• pp.777-784
• /
• 2022

• Steel and Composite Structures
• /
• 제12권6호
• /
• pp.523-540
• /
• 2012

It was clear from the former researches on reinforced concrete filled tubular steel (RCFT) structures that RCFT structures have different performance than concrete filled steel tubular (CFT) structures. However, despite of that, load-sharing ratio of RCFT is evaluating by the formula and range of CFT given by JSCE. Therefore, the aim of this investigation is to study the load-sharing ratio of RCFT columns subjected to axial compressive load by performing numerical simulations of RCFT columns with the nonlinear finite element analysis (FEA) program - ADINA. To achieve this goal, firstly proper material constitutive models for concrete, steel tube and reinforcement are proposed. Then axial compression tests of concrete, RC, CFT, and RCFT columns are carried out to verify proposed material constitutive models. Finally, by the plenty of numerical analysis with small-sized and big-sized columns, load-sharing ratio of RCFT columns was studied, the evaluation formulas and range were proposed, application of the formula was demonstrated, and following conclusions were drawn: The FEA model introduced in this paper can be applied to nonlinear analysis of RCFT columns with reliable results; the load-sharing ratio evaluation formula and range of CFT should not be applied to RCFT; The lower limit for the range of load-sharing ratio of RCFT can be smaller than that of CFT; the proposed formulas for load-sharing ratio of RCFT have practical mean in design of RCFT columns.

• 디지털융복합연구
• /
• 제17권4호
• /
• pp.65-73
• /
• 2019

연구는 부채비율을 종속변수로 하고 ROE(자기자본 이익률), 매출액, 유동비율, 자본총계, 운임지수인 SCFI(Shanghai Containerized Freight Index)를 독립변수로 하여 패널회귀분석을 실시하였다. GLS 분석결과, 유동비율의 경우 부채비율에 부(-)의 영향을 끼쳤고, 매출액의 경우 부채비율에 정(+)의 영향을 끼쳤다. 또한 자본총계는 부채비율에 부(-)의 영향을 미쳤다. 하지만 ROE의 경우 가설과는 다르게 부채비율에는 부(-)의 영향을 끼쳤고, SCFI지수는 유의미하지 않았다. 본 연구의 시사점으로 글로벌 선사의 부채비율이 높아질수록 글로벌 선사가 규모의 경제를 달성해 매출이 증가한 것을 확인했다. 하지만 타인자본 투입을 통한 규모의 경제실현은 매출액 증가에는 도움은 되지만, 당기순이익에는 영향을 미치지 못함을 확인하였다. 선사는 영업력을 확대하고 대형 컨테이너선을 확보하는 등의 화주 신뢰성을 확보하는 전략에 병행해야 한다. 향후 연구에서는 환율, 세계 경제 성장률, 제조업 생산지수 등을 고려한 분석이 필요하다.

• Structural Engineering and Mechanics
• /
• 제33권3호
• /
• pp.373-385
• /
• 2009

The purpose of this paper is to study shear locking-free parametric earthquake analysis of thick and thin plates using Mindlin's theory, to determine the effects of the thickness/span ratio, the aspect ratio and the boundary conditions on the linear responses of thick and thin plates subjected to earthquake excitations. In the analysis, finite element method is used for spatial integration and the Newmark-${\beta}$ method is used for the time integration. Finite element formulation of the equations of the thick plate theory is derived by using higher order displacement shape functions. A computer program using finite element method is coded in C++ to analyze the plates clamped or simply supported along all four edges. In the analysis, 17-noded finite element is used. Graphs are presented that should help engineers in the design of thick plates subjected to earthquake excitations. It is concluded that 17-noded finite element can be effectively used in the earthquake analysis of thick and thin plates. It is also concluded that, in general, the changes in the thickness/span ratio are more effective on the maximum responses considered in this study than the changes in the aspect ratio.