• Proceedings of the KSME Conference
• /
• 2004.04a
• /
• pp.1761-1766
• /
• 2004

Recently, Plastic optical products are widely used. Injection molding process has advantages of low cost and high productivity. However, it remains a residual birefringence and residual stress by difference cooling. The present study focused on measuring birefringence in optical plastic parts using interference color pattern. The main idea of an analysis comes from chromatic aberration which is caused by difference light wavelengths. As a result, a complete system measuring the high order 2-D birefringence pattern was built. Further investigation is under way to improve the accuracy of birefringence measurement system by diode laser.

• Journal of Korea Port Economic Association
• /
• v.19 no.2
• /
• pp.33-53
• /
• 2003

The purpose of this paper is to investigate the effectiveness of port investemnt which is one of the important elements for measuring the port efficiency by using congestion approach of DEA(Data Envelopment Analysis). Congestion is said to be present when increases in inputs result in input reductions. Congestion approach takes the forms of weak input disposability and strong input disposability. Empirical analysis by using congestion approach in this paper identified inefficiencies in the inputs including port investment, and indicated inefficient ports like the ports of Sokcho, Gunsan, Pohang, and Seoguipo which shows the large amount of slacks with congestion especially in terms of port investment. Therefore these ports should examine the reason about the inefficiency of port investment. The main policy implication based on the findings of this study is that The Ministry of Maritime Affairs & fisheries in Korea should introduce congestion approach when the amount of port investment to each port is decided.

• Industrial Engineering and Management Systems
• /
• v.13 no.2
• /
• pp.210-220
• /
• 2014

This article describes a 2-in-1 methodology utilizing simulation optimization technique and Data Envelopment Analysis in measuring an accurate efficiency score. Given the high level of stochastic data in real environment, a novel methodology known as Data Collection Budget Allocation-Data Envelopment Analysis (DCBA-DEA) is developed. An example of the method application is shown in banking institutions. In addition to the novel approach presented, this article provides a new insight to the application domain of efficiency measurement as well as the way one conducts efficiency study.

• Journal of Power Electronics
• /
• v.17 no.4
• /
• pp.963-971
• /
• 2017

Torque ripple is one of the major sources inducing vibration and noise in brushless DC motors. This is especially true in applications such as the spindle motors used in hard disk drives. However, the relationship between torque ripple and acoustic noise/vibration is quite complicated. This paper presents a way to investigate this relationship with acoustic noise measurement and analysis. Results obtained with three different drive modes are used in the analysis. The results show that the acoustic noise analysis is very helpful in designing a high-performance drive strategy for BLDC motors.

• IEMEK Journal of Embedded Systems and Applications
• /
• v.6 no.5
• /
• pp.327-333
• /
• 2011

Intelligent robots are widely needed in various areas of industry from extremely dangerous environments to service tasks. For autonomous mobile robots, it is significant to move itself safely to a destination point, recognizing its surroundings. Advances in sensor technology and its applications are achieved in order to develop an intelligent robot. In this paper, a mobile robot with a path-finding algorithm is presented. The path-finding algorithm is the one that does not only find a path to designated destination and also recognizes obstacles on the way, calculating its distance. 10 ultrasonic sensor are mounted on the front and rear of the mobile robot to figure out its position. Specular reflection and wide viewing angle, which are inherent characteristics of ultrasonic waves, cause errors in measuring distance.

• International Journal of Computer Science & Network Security
• /
• v.22 no.7
• /
• pp.43-50
• /
• 2022

Continuous development is the key of development issue in developing nations. Smart city measurement is prevalently carried through in the cities in which the nations have been classified as industrialized countries. In addition, cities in Europe becomes the models of smart city system. Smart city concept used in the cities in Europe applies six predominant features i.e. smart economic, smart mobility, smart environment, smart people, smart living, and smart governance. This paper focuses on figuring out city' development strategy in developing nations particularly Indonesia in regard with European Framework by way of Multi Expert Multi Criterion Decision Making (ME-MCDM). Recommendation is resulted from the tests using the data collected from one of the metropolis cities in Indonesia, whereby issuing recommendation must firstly implement smart education, secondly communication, thirdly smart government, and fourthly smart health, as well as simultaneously implement smart energy and smart mobility.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.18 no.3
• /
• pp.49-59
• /
• 2018

Smart grid system has been deployed fast despite of legal, business and technology problems in many countries. One important problem in deploying the smart grid system is to protect private smart meter readings from the unbelievable parties while the major smart meter functions are untouched. Privacy-preserving involves some challenges such as hardware limitations, secure cryptographic schemes and secure signal processing. In this paper, we focused particularly on the smart meter reading aggregation,which is the major research field in the smart meter privacy-preserving. We suggest a noisy weighted aggregation scheme to guarantee differential privacy. The noisy weighted values are generated in such a way that their product is one and are used for making the veiled measurements. In case that a Diffie-Hellman generator is applied to obtain the noisy weighted values, the noisy values are transformed in such a way that their sum is zero. The advantage of Diffie and Hellman group is usually to use 512 bits. Thus, compared to Paillier cryptosystem series which relies on very large key sizes, a significant performance can be obtained.

• Journal of the Korean Society of Costume
• /
• v.28
• /
• pp.99-112
• /
• 1996

In this study I purpose a new approach to the study of Korean costume history which includes a statistical method used in the prac-tical measurement of excavated Po's and the analysis of their quantitative changes. In the framework used in this study I de-pend on the nineteen variables picked out from the typological and chronological analysis of excavated clothes. The interrelationship of the variables as well as the standard of each part and its deviation in other forms are may main concern. Other methods are also very useful in my thesis: Correlation analysis Regression analysis Discrimination analysis Cluster analysis Discrimination analysis Cluster analysis Factor analysis One way analysis of variance. The findings of my study can be summarized as follows: 1. Every type of po has a general tendency to have more broadened sleeves while it does not show any considerable changes in the total length and in the width of armholes. 2. In the Correlation analysis each part of Po's is handled separately accordign to its chronology and type. The Regreesion analysis makes it possible to provide the sizes of miss-ing parts in excavated clothes and the numeri-cal value of each part needed in the pattern making. 3. The Discrimination analysis of the Po's whose types are unknown leads to the con-clusion that Chongsam and Chikryong Po are classified into Chikryong Po whereas Hongui is classified into Jooui In addition I propose discriminational function by which the age classification is possible discovering the variables associated with time change. 4. Five items-Gerneral Park's clothes Taewongun's clothes and three others produced later for the purpose of preserving Korean costume are proved to be in a differ-ent group and hence analyzed separately in the visual grouping of changui which is done after the cluster analysis and the factor analysis. 5. The results of the one way analysis of variance reveal that there is a difference in each part from period: the back width the sleeve length the sleeve width thelean fig-ure the breasttie length the breasttie width outside quesset upper inside quesset lower outside neckband length insideneckband length etc.

• Journal of Advanced Navigation Technology
• /
• v.16 no.4
• /
• pp.619-626
• /
• 2012

One-way Network-RTK(Real Time Kinematics) is considered as a method which can satisfy moving vehicle's recently-required high accuracy and mobility. When we use one-way Network RTK for vehicle navigation, multiple cells-based system is required to provide the service continuously in wide area. The rover which moves through various cells inevitably experiences a correction discontinuity, which is not eliminated by the DD(Double Difference) method and to cause 13cm(horizontal) and 48cm(vertical) position error. We suggest three solutions to reduce this discontinuity, which are identification of master RS with neighbor networks, duplication of communication module to receive corrections from other cells, and ambiguity adjustment between neighbor cells. All of our suggestions reduce the error to 1/4 wavelength in measurement and 3cm in position-domain, and we suggest the ambiguity adjustment is the best when we consider the extendibility of service area and the cost of rover device.

• Journal of The Korean Society of Integrative Medicine
• /
• v.2 no.2
• /
• pp.79-88
• /
• 2014

Purpose: This study investigated the relationship between smartphone addiction propensities and compare muscle activity of the forearms and brain wave depend on the type of smartphone when inputting text messages. Method: We used an EMG to measure the change in muscle activity by attaching pads to the four muscles in both forearms of all 16 participants. We simultaneously conducted EEG measurements by observing the changes in alpha and beta waves recorded from electrode attached to both ears and the forehead of the participants. The participants had to input a given text using three different types of smartphones for ten minutes each. Result: The comparison of the EMG when inputting text involved a one way analysis of variance and the results showed that the iPad3 was highest for muscle activity followed by GALAXY Note2 and iPhone4. For EEG measurement, a one way analysis of variance was also used and the results showed iPhone4 was higest followed by GALAXY Note2 and finally iPad3 for EEG stress score. Conclusion: The results are thought to be used as reference data for smart phone users.