• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.1
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• pp.10-17
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• 2013

In this paper, a new active damping method of LCL filter without capacitor voltage sensors is proposed for 3 phase PWM Inverter. Normally, L filter or LCL filter is used as an output filter of grid connected PWM inverter. An LCL filter has more excellent performance than L filter to reduce harmonic current, so the small inductance value can be used. However, the resonance problem in LCL filter is happen due to the zero impedance by the addition of LC branch. To solve the resonance problem, the various active damping method has been proposed so far. Generally, the virtual resistor active damping methods is required to additional hardware sensors for measurement of capacitor voltage and current. In this paper, the new active damping method is proposed without any capacitor voltage or current sensors. In the proposed method, the resonance component of the capacitor voltage of LCL filter can be observed by a simple MRAS(Model Reference Adaptive System) observer without additional hardware sensors, and this component is suppressed by feedforward compensation. The validity of the proposed method is proven by simulation and experiment on the 3-phase PWM inverter system.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.2
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• pp.324-330
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• 2015

Energy Saving Methods in existing railway vehicle are considered by active approach such as regenerative energy storage and utilization, eco driving, etc. On the other hands, energy saving measures in railway station are operated by passive method such as reduction of operating time in ventilation system, cooing system and power equipment. To reduce energy and for independence in railway system, it requires an active energy saving measures. It needs to its own power source besides the power source of electric supply company such as renewable energy and regenerative energy and take the advantage of power storage system and stored power are used in optimum time. This paper deal with 3-level NPC inverter and T-type NPC inverter that used in various multi-level topology applicable to the railway system.

• Journal of Electrical Engineering and Technology
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• v.11 no.1
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• pp.257-264
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• 2016

In this paper, new electric railway feeding system which has active transformer is modeled for evaluating the steady state analysis using PSCAD/EMTDC. Equivalent models including power supply, feeder, train and transformers are proposed for simplifying the model of the feeding system in high speed electric railway. In case study, simulation results applied to proposed model are compared with the conventional and new systems through the catenary voltage, three-phase voltage of PCC (Point of Common Coupling) and the efficiency of regenerative braking energy.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.1558-1566
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• 2010

After the establishment of 'Staggers' Rail Legislation' in 1980, which established an atmosphere of free competition in rail freight transportation market, freight railway in America became larger and the proportion of freight railway in the market increased. In 2008, it took up 43% of the transportation market based on tonne/mile unit and the productivity of freight rail increased. On the other hand, in the case of Korea, the competing atmosphere is being set up under the influences of the renovation of the rail transportation industry in 2004. However, to make the rail transportation market more active and become more advanced, a lot of efforts are required to build a stronger foundation of free competition atmosphere. In this paper, we have deducted the political implications on the establishment of strengthened competition in Korean rail transportation industry from reviewing what kind of changes the rail transportation market in America went through and how it was developed. In this case, we have focused on the changes in industrial trend towards the restriction policy. Also influences of the deregulation policy after 1980 on the enhanced market efficiency were reviews.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.29 no.2
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• pp.69-75
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• 2023

Purpose: This study examined the distance between the coracoid process and the humeral head using an ultrasonography device when shoulder active contraction were applied according to the guided direction in the end range of shoulder mobilization. This study aims to provide essential data on treating shoulder disease patients. Methods: The subjects of this study were 20 adults with healthy shoulder joints. ultrasonography (US) equipment was used to examine shoulder joint mobilization under two conditions: (1) anteroposterior (AP) joint mobilization and (2) superoinferior (SI) joint mobilization. Shoulder active contraction was assessed in the end range. The distance between the coracoid process and the humeral head was measured. A linear probe was used for US; the frequency was set to 7.5MHz, and the US image display method was set to B-mode. The US measurement values were measured in (1) the starting position, (2) the end range position, and (3) the end range position of the shoulder active contraction, and the moving distance was drawn in a straight line through the US image. The distance was determined as the measurement value, and the average values were compared. Reults: The results were as follows: (1) the measured AP Joint mobilization increased by an average of .52cm from the end range of the joint mobilization with shoulder active contraction; (2) the measured SI Joint mobilization increased by an average of .49cm from the end range of the joint. Conclusion: When shoulder mobilization is applied, the distance between the coracoid process and the humeral head increases when muscle contraction occurs through shoulder active contraction in the end range, according to the therapist's guidance. Therefore, shoulder mobilization combined with shoulder active contraction is an effective treatment method for patients with shoulder injuries.

• Journal of the Korean Society of Safety
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• v.33 no.4
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• pp.98-104
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• 2018

Macroscopic accident analyses have been conducted to incorporate transportation safety into long-term transportation planning. In macro-level accident prediction model, exposure variable(e.g. a settled population) have been used as fundamental explanatory variable under the concept that each trip will be subjected to a probable risk of accident. However, a settled population may be embedded error by exclusion of active population concept. The objective of this research study is to develop macro-level accident prediction model using floating population variable(concept of including a settled population and active population) collected from mobile phone data. The concept of accident prediction models is introduced utilizing exposure variable as explanatory variable in a generalized linear regression with assumption of a negative binomial error structure. The goodness of fit of model using floating population variable is compared with that of the each models using population and the number of household variables. Also, log transformation models are additionally developed to improve the goodness of fit. The results show that the log transformation model using floating population variable is useful for capturing the relationships between accident and exposure variable and generally perform better than the models using other existing exposure variables. The developed model using floating population variable can be used to guide transportation safety policy decision makers to allocate resources more efficiently for the regions(or zones) with higher risk and improve urban transportation safety in transportation planning step.

• Journal of the Korean Professional Engineers Association
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• v.34 no.1
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• pp.49-52
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• 2001

It is expected that transportation sector will develope to a systematic and multi-disciplinary way in which transportation, information and electronic technologies are harmonized. This will be the way that the 21st century demand. To be prepared for such development, sharing of information from different sources through a integrated approach is essential. Also an active role of specialized staff are required to achieve a integrated control and management. The specialized staff should do his best for his task with appropriate specialty, a sense of responsibility, a progressive mind and a vision. He also make much effort to enhance and keep up-to-date his specialty. Then we can modestly look forward to a specialized Information society in the 21s1 century.

• Journal of Magnetics
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• v.22 no.1
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• pp.162-167
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• 2017

Magnetic spiral-type microrobots, which are driven by a rotating magnetic field, have excellent locomotive abilities, whereas their medical applications are limited in the terms of function, such as the ability to drill in blood vessels. In this study, we propose a new robot with superior applications using a magnetic spiral-type machine. The proposed robot can be applied to stent transportation and installation without a catheter. In particular, the robot can be applied to the cardiovascular system, cerebrovascular disease, and nonvascular stent applications depending on the robot size. The robot consists of two independent spiral-type machines and four magnets in total. We controlled directions of thrust force of the two machines, respectively, for active locomotion with a task. We conducted a preliminary validation of the proposed robot for stent transportation and installation through experimental analyses.

• Proceedings of the KIPE Conference
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• 2015.07a
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• pp.29-30
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• 2015

본 연구는 배터리 전력저장장치를 위한 새로운 양방향 컨버터에 대한 기술이다. 제안된 기술은 절연형 토플로지로 10배 이상의 높은 승/강압비, soft-switching 기능으로 대용량/저전압 배터리를 구성할 수 있다. 기존에 사용되던 DAB(Dual Active Bridge)의 단점은 배터리 충/방전 전류가 정전류(Constant Current)가 아닌 +/-가 반복되는 양방향의 불연속적인 파형이라는 것이다. 이것은 배터리 충/방전 제어명령이 정전류 형태의 상수 값이라는 것을 고려하면 그대로 사용하기에는 문제가 될 수 있다. 그러므로 Current-source type의 변형된 DAB 토플로지를 사용하여 전류원 형태의 정전류 제어가 가능하다는 것이 장점이 된다. 제안된 기술의 검증을 위해 컴퓨터 시뮬레이션과 실험을 통하여 그 성능을 입증하였다.

• Proceedings of the IEEK Conference
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• 2000.07b
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• pp.773-776
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• 2000

Traffic monitoring plays an important role in intelligent transportation systems. It can be used to collect real-time traffic data concerning traffic flow. Passive shadows resulted from roadside buildings or trees and active shadows caused by moving vehicles, are one of the factors that arise errors in vision based vehicle detection. In this paper, a land mark based method is proposed for vehicle detection and shadow rejection, and finally vehicle count are achieved based on the land mark detection method.