• 제어로봇시스템학회논문지
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• 제14권8호
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• pp.800-808
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• 2008

This paper presents a localization algorithm of the outdoor wheeled mobile robot using the sensor fusion method based on indirect Kalman filter(IKF). The wheeled mobile robot considered with in this paper is approximated to the two wheeled mobile robot. The mobile robot has the IMU and encoder sensor for inertia positioning system and GPS. Because the IMU and encoder sensor have bias errors, divergence of the estimated position from the measured data can occur when the mobile robot moves for a long time. Because of many natural and artificial conditions (i.e. atmosphere or GPS body itself), GPS has the maximum error about $10{\sim}20m$ when the mobile robot moves for a short time. Thus, the fusion algorithm of IMU, encoder sensor and GPS is needed. For the sensor fusion algorithm, we use IKF that estimates the errors of the position of the mobile robot. IKF proposed in this paper can be used other autonomous agents (i.e. UAV, UGV) because IKF in this paper use the position errors of the mobile robot. We can show the stability of the proposed sensor fusion method, using the fact that the covariance of error state of the IKF is bounded. To evaluate the performance of proposed algorithm, simulation and experimental results of IKF for the position(x-axis position, y-axis position, and yaw angle) of the outdoor wheeled mobile robot are presented.

• 한국융합학회논문지
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• 제8권3호
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• pp.225-235
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• 2017

기업은 자기주식을 시장에서 직접 취득하는 방법과 신탁계약을 통한 간접 취득방법을 선택할 수 있는데, 두 방식에는 제도적인 차이가 존재하며, 따라서 자기주식을 취득하는 두 방식은 시장에 서로 다른 신호를 전달할 수 있다. 본 논문은 자사주 매입 방법과 추정자기자본비용(ICOE) 사이의 관계를 실증적으로 분석하였고, 연구의 결과는 다음과 같다. 첫째, 자사주 매입을 공시한 기업의 자기자본비용이 자사주 매입을 공시하지 않은 기업의 자기자본비용보다 통계적으로 유의미한 수준에서 낮게 나타났다. 이 결과는 여유현금흐름가설이나 자사주 매입이 체계적 위험과 투자지출의 감소에 따라 자기자본비용이 감소한다는 주장과 일치한다. 둘째, 자기주식을 직접 취득한 기업은 간접 취득한 기업에 비해 통계적으로 유의미하게 낮은 자기자본비용을 가지는 것으로 나타났다. 이러한 결과들은 시장참여자들이 서로 다른 자사주 매입 방식이 가지는 융합적 신호효과를 정확히 판단하여 이를 자기자본비용에 적절히 반영한다는 것이다.

• 영어어문교육
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• 제11권2호
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• pp.1-18
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• 2005

This study is a preliminary investigation of the nature of discourse marker acquisition in Korean American speakers of English. Discourse markers are of interest because they are not an aspect of language taught through formal instruction either to native or non-native speakers. Therefore, discourse marker use serves as indirect evidence of face-to-face interaction with native speakers and an indicator of integration. In this light, the present study examines the presence of discourse markers in Korean Americans. The markers chosen for analysis were you know, like, and I mean. The data consist of spontaneous speech elicited from interviews. Sociolinguistic variables such as age, sex, and generation (i.e., $1^{st}$, 1.5, $2^{nd}$) were examined. Results show that there appears to be interaction between the variables and discourse marker use. While all speakers showed variable acquisition of markers, younger, female, and 1.5 generation speakers were found to use discourse markers more than other speakers. Although discourse marker use is optional and thus not a linguistic feature that must be necessarily acquired, it is clear that use is pervasive and acquired differentially by English speakers irrespective of whether they are native or not.

• 대한가정학회지
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• 제36권5호
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• pp.29-46
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• 1998

This study investigates how the consumers utilize the elements of information search and how consumers are satisfied with them. For this study, drives who have bought their own cars in two years were chosen for subjects of investigation. And samples were interviewed with an organized questionaire from July 8 to July 27, 1996. 300 samples were used for the final analysis. The major results from this study are as follows. 1) In general information search, consumers get a great deal of information from a talk their friends, neighbors, or colleagues, and they obtain information from an experienced person or a professional. In using sources of information search, they made the best use of their experiences, which is the sources of internal information, and for the second, they used advertising and the explanation of a salesman. In using the contents of information search, they made the best use of information about the merits and demerits in each attribute. In using the method of information search, the mixed search 1 method was used the most, and the attribute search method was used. 2) The casual relationship between the general satisfaction for the products and the relative variable was investigated. An age, the time pressure, the information of the products had a direct and indirect influence on the general for the products. The perceived risk, the number of inquiring activity, a shop and the buying method had a direct influence on the general for the products. An indirect influence was showed in the general satisfaction for the products through the medium of inquiring activity, a shop, and buying method.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.299-302
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• 2002

Characteristics of the twin fluid spray with ultrasonic forcing are examined in order to obtain the high efficiency of cold fog spray of the automatic pest control machine which has been widely used for the equipment cultivation recently. An electrostrictive vibrator of PZT BLT and a magnetostrictive vibrator of ${\pi}type$ with 28 kHz are applied as the ultrasonic transducer. All experiments are made and observed in 4 methods of spray ; a conventional spray method without ultrasonic forcing, an indirect vibration method with ultrasonic forcing, an improving duality method by ultrasonic forced within liquid, and a combined use method with both of the indirect vibration method and the improving quality method. In results, It was clarified that the ultrasonic effects the atomization of spray droplets and its efficiency is about $10{\%}$ and especially much more in the case of the combined use method.

• 한국도로학회논문집
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• 제20권4호
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• pp.27-34
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• 2018

PURPOSES : The objective of this study is to evaluate the physical properties of recycled asphalt mixtures reinforced with glass fiber. METHODS : Firstly, mixing design was conducted on recycled asphalt mixture for use of 50% recycled aggregate. Various laboratory tests were performed on four types of recycled asphalt mixtures with different glass fiber content to evaluate the physical properties. The laboratory tests include indirect tensile strength test, dynamic modulus test, Hamburg wheel tracking test and tensile-strength ratio to evaluate cracks, rutting and moisture resistance of mixtures. RESULTS : The indirect tensile strength of fiber reinforced glass increased about 139.4%. As a result of comparing the master curves obtained by the dynamic modulus test, the elasticity was low in the low temperature region and high in the high temperature region when the glass fiber was reinforced. The glass fiber contents of PEGS 0.3%, Micro PPGF 0.1% and Macro PPGF 0.3% showed the highest moisture resistance and rutting resistance. CONCLUSIONS : The test results show that use of glass fiber reinforcement can increase the resistance to cracking, rutting, and moisture damage of asphalt mixtures. It is also necessary to validate the long-term performance of recycled asphalt mixtures with glass fiber using full scale pavement testing and field trial construction.

• Journal of Biosystems Engineering
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• 제27권4호
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• pp.317-326
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• 2002

Characteristics of a twin-fluid spray with ultrasonic vibration were examined in order to obtain a high efficiency of cold-fog spray of the automatic pest control machine which has been widely used in protected horticulture recently. An electrostrictive vibrator of PZT BLT and a magnetostrictive $\pi$-type vibrator were used applied as the ultrasonic transducers with a frequency of 28 kHz. All experiments were conducted in 4 methods of spray ; a conventional spray method without ultrasonic forcing, an indirect vibration method with ultrasonic forcing, an improving-quality method by ultrasonic forced within liquid, and a combined-use method with both of the indirect vibration method and the improving quality method. It was found that the ultrasonic energy increased the atomization efficiency of spray droplets about 10% and especially much more in the case of the combined-use method.

• 보건행정학회지
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• 제22권4호
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• pp.497-521
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• 2012

Objectives This study aimed to investigate the effect of social capital, health risk behavior and health status on medical care utilization by the elderly. The data and Research method Data were obtained from the 4th wave survey of the Korea Welfare Panel Study. 4,087 household members aged 65 years and over were subject to analysis. Descriptive statistics are used to describe the basic features of the data in a study. we performed a structural equation modeling(SEM) analysis to evaluate the effect of social capital and mediating effect of health risk behavior and health status. Results Results showed that factors related to medical care utilization of the elderly were different depending on types of service (inpatient and outpatient service) except health status. Age, higher social capital, more health-risk behavior and poorer health status were associated with increased use of inpatient service. Social capital was found to have a positive direct effect on it. Also, social capital had an indirect effect on reducing use of inpatient services by improving health status. On the other hand, lower age and higher household income tended to increase use of outpatient service, while higher social capital and higher health status were inversely related. Social capital had a direct effect and an indirect effect on reducing use of outpatient service and, at that time, health status played a mediating role. Conclusions Social capital may contribute to improve health status and indirectly reduce medical care utilization of the elderly by enhancing their health status. These results provide evidence that more policy and strategy considerations should be needed for the elderly to strengthen their social capital in order to enhance their levels of health and more efficient utilization of medical care.

• 한국정보시스템학회지:정보시스템연구
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• 제10권1호
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• pp.279-301
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• 2001

This study was examined empirically the relationship between exogenous and endogenous variables to use internet shopping malls. Exogenous variables in our model are retrieval simpleness, quality of order treatment, web reputation, update and system quality and endogenous variables are perceived usefulness, perceived ease of use and intention of using internet shopping malls. The results of the path analysis are shown as follows. All exogenous variables have a direct effect on perceived ease of use while both retrieval simpleness and update has a direct effect on perceived usefulness. The perceived ease of use has a direct effect on the intention of using internet shopping malls and has a indirect effect on the intention through perceived usefulness. Especially, web reputation among the exogenous variables has the strongest impact on the perceived ease of use and retrieval has the strongest impact on the perceived usefulness.

• Smart Structures and Systems
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• 제15권5호
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• pp.1203-1214
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• 2015

This paper deals with the experimental validation of the use of PVDF Patches for the assessment of spatial derivatives of displacement field. It focuses more exactly on the shear Force Identification by using Specific forms of PVDF patcHes (FISH) on beams. An overview of the theoretical approach is exposed. The principle is based on the use of the weak form of the equation of motion of the beam which allows the shear forces to be extracted at one edge of the sensor when this last has a specific form. The experimental validation is carried out with a cantilever steel beam, excited by a shaker at its free boundary. The validation consists in comparing the shear force measured by the designed sensor glued at the free edge and the directly measured force applied by the shaker. The sensor is made of two patches, called the "stiffness" patch and the "mass" patch. The use of both patches allows one to identify correctly the shear force on a large frequency domain. The use of only the stiffness patch is valid in the low frequency domain and has the advantage to have a frequency-independent gain that allows its use in real time.