• Journal of Electrical Engineering and Technology
• /
• 제13권5호
• /
• pp.1769-1777
• /
• 2018

This paper proposes a method for optimal placement of Phasor Measurement Units (PMUs) considering system configuration and its attributes during the planning phase of PMU deployment. Each bus of the system is assessed on four diverse attributes; namely, redundancy of measurements, rotor angle and frequency monitoring of generator buses, reactive power deficiency, and maximum loading limit under transmission line outage contingency, and a consolidated 'degree of criticality' is determined using Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS). The major contribution of the proposed work is the development of modified objective function which incorporates values of the degree of criticality of buses. The problem is formulated as maximization of the aggregate degree of criticality of the system. The resultant PMU configuration extends complete observability of the system and majority of the PMUs are located on critical buses. As budgetary restrictions on utilities may not allow installation PMUs even at optimal locations in a single phase, multi-horizon deployment of PMUs is also addressed. The proposed approach is tested on IEEE 14-bus, IEEE 30-bus, New England (NE) 39-bus, IEEE 57-bus and IEEE 118-bus systems and compared with some existing methods.

• 산업기술연구
• /
• 제26권B호
• /
• pp.83-92
• /
• 2006

A probabilistic analysis model. one of reliability analysis methods introducing the concept of variables, was developed to investigate the uncertainty of dominant factors influencing the degree of consolidation in the radial consolidation theories. Based on the developed probabilistic analysis model, sensitivity study of those factors was performed to find their trends of affecting the degree of consolidation in the vertical drain method. Various radial consolidation theories, proposed by Barron(1948), Hansbo(1979), Yoshikuni(1979) and Onoue(1988), were used for this parametric study with the influencing factors such as size of smear zone, reduction ratio of permeability in the smear zone, discharge capacity, permeability for horizontal flow and coefficient of consolidation for horizontal flow. As results of this sensitivity study, for the given consolidation theory, contribution of each factor to the degree of consolidation was figure out and compared to each other. For the given value of each factor, the sensitivity to the degree of consolidation in the various theories was evaluated and their applicability and limitations were assessed.

• 한국항해항만학회지
• /
• 제48권2호
• /
• pp.78-87
• /
• 2024

To quantitatively assess the correlation between subsystems within a port cluster and the overall coordinated development of the port group, the current paper evaluates the coordinated development of port clusters. First, we construct an evaluation index system for the coupling and coordination of port clusters. Next, we introduce the contribution index of port subsystems, coupling degree, and coupling coordination degree functions to formulate a coupling coordination evaluation model for the port cluster. Finally, we use the Yangtze River Delta port cluster as a case study for validation, specifically using empirical data from 2012 to 2021. The findings reveal distinct phased characteristics in the coupling and coordination of port clusters in the Yangtze River Delta, marked by a notable transition from "maladjustment" to "coordination." Further, sustained high coupling values over a decade indicate a significant level of competition and cooperation among ports within the Yangtze River Delta port cluster. Over time, this competitive and collaborative dynamic has progressively evolved toward a more positive and structured direction. Lastly, it is expected that the evaluation model proposed in this paper can be extrapolated to other port clusters to gauge the extent of coordinated development, thereby facilitating horizontal comparisons and vertical analyses.

• 유통과학연구
• /
• 제15권2호
• /
• pp.69-78
• /
• 2017

Purpose - As recently social contributions of firms are positioned as key strategic actions, it is demanding to review the effects of social contributions on overall corporate management. The research aims to effects of social contributions on social values and word of mouth in firm level and product level. Further roles of consumer identification with firm and product eco-friendliness are also analyzed. Research design, data, and methodology - The paper conducted a survey in which two scenarios are used for manipulating the degree of corporate social contributions. The survey sample consist of 165 undergraduate and graduate students in a university, located in Seoul. For analyzing data, analysis of variance is applied, in conjunction with analysis of moderating effects, through version 23 of SPSS statistical package. Results - In the firm level, social contributions by firms have a positive effect on social values of firms. Consumer identification showed a moderating role in the effect. Social value of the firm with passive social contribution perceived by respondents with a high degree of identification was higher than social value of the firm with active social contribution perceived by respondents with a low degree of identification. Corporate social value has positive effect on word-of-mouth of firms. In the product level, social contributions by firms has a positive effect on social values of product. Product eco-friendliness showed a moderating role in the effect. For eco-friendly product, social values are higher in the firm with active social contributions than in the firm with passive social contributions. However, for non eco-friendly product, the difference in social values between the two firms does not exist. Product social values has positive effect on intention for WOM of products. WOM of eco-friendly products with low social value showed no difference with WOM of non eco-friendly products with high social value. Conclusions - These results imply that firms should enhance consumer identification with firm in making social contributions for optimizing corporate social value and enhancing word-of-mouth(WOM). Managerial implications of the results suggest it would be more effective to improve social value of product by active social contributions for increasing word-of-mouth(WOM) of product.

• 한국작물학회지
• /
• 제34권3호
• /
• pp.229-234
• /
• 1989

황색종잎담배의 추엽 품질등급별 수량 비율과 기상요인과의 관계를 분석한 바 그 결과는 다음과 같다.1. 평균기온의 경우 1,2 등엽 수량비율은 4월 하순 및 7월상순의 특성치와 5%, 5월하순의 특성치와는 1% 수준의 부상관을 나타냈다. 2. 최고기온의 경우 1,2등엽 수량비율은 5월 하순에서부터 7월상순까지의 순별 특성치와 부상관을 나타냈다. 3. 최저기온의 경우는 1,2등엽 수량비율은 4,5하순의 특성치와 1% 수준의 부상관, 5월상순, 6월상순, 7월중순의 특성치와는 1% 수준의 정상관을 나타냈다. 4. 평균기온의 영향도순위는 4,5 등엽 수량비율의 경우 정방향은 7월하순 > 5월상순이고 부방향은 5월하순과 7월상순이였다. 5. 최저기온의 부방향 영향도순위는 4, 5 등엽 수량비율의 경우 5월상순 > 6월상순 > 6월하순이였다. 6. 일조시수는 1, 2등엽 수량비율의 경우 4월중순과 7월중순을 제외한 전생육시기의 순별 특성치와 유의상관을 나타냈다. 7. 일조시수의 정방향 영향도순위는 5월하순 > 4월하순 > 7월하순 > 7월중순이였고 부방향 영향도순위는 6월하순 > 5월상순 > 6월중순 > 5월중순이였다. 8. 강수량은 1, 2등엽 수량비율의 경우 정방향 영향도순위는 6월하순 > 7월중순 > 7월하순이고 부방향 영향도 순위는 4, 5월하순이였다.

• 한국식생활문화학회지
• /
• 제9권3호
• /
• pp.289-301
• /
• 1994

The purpose of this study was to investigate housewives' perception, interest and consumption of organic food, and to identify the variables influencing on them. The sample was selected from 411 housewives living in Seoul from 1st of September to 20th of September in 1993. Used statistical methods were frequency, percentage, mean, Cronbach's ${\alpha}$, factor analys, ANOVA, Duncan's multiple range test, t-test, correlation, regression analysis and Path analysis. The major results are as follows: 1) Housewives' perception degree of organic food in its variety, easy availability and contribution to health was relatively high level, but price level, reliability and packing condition was somewhat low level. Out of housewives' many images of organic food, taste health care, quality and necessity factors can be implicated. 2) Housewives' interest degree of organic food is somewhat high level 3) Housewives' consumption degree of organic food was relatively low level and was affected by their perception of oraganic food. 4) Frequency to use seasonings was the major independent variable which influenced to housewives' perception degree of organic food, while recognition on enviornmental contamination was the major independent variable which influenced to their interest degree of organic food, and their total perception on organic food was the major independent variable which influenced to their consumption degree of oragnic food. Therefore, it is considered that their total perception to it can decide the demand of organic food 5) Housewives' perception and interest degree of it was the major intervening variable which influenced to their consumption degree of oragnic food.

• 유통과학연구
• /
• 제14권8호
• /
• pp.129-138
• /
• 2016

Purpose - The present study theoretically reviews the use of power norm according to the cultural orientation of consumers to categorize the shopping value that corresponds to the use of the power norm when consumers use local food stores. Research Design, Data, and Methodology - Based on the data collected from the survey to 130 undergraduates, salaried men and people at large, the group with cultural value orientation was divided further into the group of horizontal individualism and that of vertical collectivism by using cluster analysis of SPSS 18.0 program. And regression analysis of SPSS 18.0 was employed to verify the hypotheses. Results - The following conclusions were shown in the empirical study. First, in the group of vertical collectivism, contribution to regional profits and competitiveness, economic value and service superiority can positively affect the attitude to the local food stores while the social responsibility activity in the community can't. In the group of horizontal individualism, however, contribution to regional profits and competitiveness, social responsibility activity, economic value and service superiority were all found to positively affect the attitude to the stores. Second, the distinctive shopping value of the stores such as escapism, entertainment value and prestige does not affect the attitude to the stores. Third, the positive effects that the stores' level of responsibility for the outgroup community can exercise on the attitude to the stores turned out to be bigger in the group of horizontal individualism than in the group of vertical collectivism. Fourth, the impact that the degree of the stores' contribution to regional profits and competitiveness has on the attitude to the stores was found to be positive in both groups. However, no difference existed in the degree of positive effects between them. Conclusions - Marketing managers of local food stores should pay more attention to managing their contribution to practical shopping value and to interests as well as competitiveness of regional society, and to persuading consumers of the horizontal individualistic group by performing responsible activities for the outgroup of local society regardless of the types of consumers' cultural orientation.

• 한국안전학회지
• /
• 제22권3호
• /
• pp.28-33
• /
• 2007

Often Regular Measurement Target 32 Spots which are distributed at Seo-gu in Incheon Metropolitan and Odour Emission Target 100 Factories based on the task instruction of Ministry of Environment in Korea were selected by considering to atmosphere phenomena and regional characteristics etc. This paper aims at building the Decreasing Prediction System of Odour which is capable of comparing and examining the concentration distribution by odour compounds, the distribution maps of odour diffusion and the contribution degree of sphere of influence, which is discharged from these above spots and factories.

• Journal of Mechanical Science and Technology
• /
• 제20권8호
• /
• pp.1183-1194
• /
• 2006

The aim of this study was to identify the characteristics of the flexion withdrawal reflex modulated by the hip angle and hip movement in spinal cord injury (SCI). The influence of the hip position and passive movement were tested in 6 subjects with chronic SCI. Each subject placed in a supine position and lower leg was fixed with the knee at 5 -45 degree flexion and the ankle at 25-40 degree plantar flexion. A train of 10 stimulus pulses were applied at 200 Hz to the skin of the medial arch to trigger flexion reflexes. From results of the regression analysis, static properties of normalized muscle activation of flexor muscles have the linear relationship with respect to hip angle (P< 0.05). In order to verify the neural contribution of flexion reflex, we compared the static and dynamic gains of estimated muscle activations with measured EMG of ankle flexor muscle. Form this study, we postulate that the torque and muscle response of flexion withdrawal reflex have linear relationship with hip angle and angular velocity.

• 대한기계학회논문집
• /
• 제19권1호
• /
• pp.14-21
• /
• 1995

General Mechanical Structures have various and complex vibration transmission paths. In order to identify the mechanism of vibration transmission. The correct estimation of exciation forces and the exact modeling of transmission paths are required. In this paper, vector synthesis technique is employed to identify the characteristics of vibration input and it's transmission to body structure for the mounting system of a compressor in a refrigerator. Vibration reduction efficiency of each transmission path is evaluated by comparing individual vector components obtained before and after the paths from experimental research. The degree of effect is used to estimate the contribution of vibration input components to total output. And this paper presents a new technique based on simulation studies using vector synthesis dragram, by which the effects of change of the magnitude and phase of transmission paths can be predicted.