• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.6
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• pp.108-113
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• 2021

Recently, a new concept of a one-touch descending lifeline has been proposed to address the drawbacks of the conventional descending lifeline, which can be easily installed and quickly evacuated in the case of a fire emergency. All separate parts for escape are initially mounted in a box, and the link-type support is spread out of the window by pushing the handle attached to the box. In this study, the proposed double square linkage mechanism was redesigned, and its safety is verified by determining an appropriate moment of inertia of the link through finite element analysis using Abaqus. The shape and assembling method of the reel and speed controller were also modified such that the safety belt was simultaneously unfolded with link-type support. Finally, the feasibility of the proposed one-touch all-in-one descending lifeline was confirmed through fabrication.

• Journal of the Korean Society of Safety
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• v.16 no.4
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• pp.65-73
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• 2001

This paper is a study on the fatigue analysis using BS5400 Part10(1980), code of practice for fatigue for a double link type level luffing jib crane which has been operated since the crane was built in 1985 at a domestic pier. South Korea. In addition, on the basis of the design lift due to fatigue analysis and the number of cracks detected from the nondestructive test the structural reliability and the residual life of the crane is predicted by evaluating the expected development of detectable fatigue oracle during the next five to ten years using Paris's Law for predicting fatigue crack growth and Gaussian probability density function to be reasonable for stress ranges below the mean values determined by laboratory tests. The statistical data used for the analysis of the structural reliability and life expectancy is given in the above referred code.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.193-197
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• 2001

This paper presents a novel circuit topology of the double two-switch forward type high frequency transformer linked soft-switching PWM DC-DC power converter with tapped inductor filters that can operate under a condition of the low peak voltage stress across the power semiconductor devices and lowered peak current stress through the transformer for some high power applications. This circuit topology of an interleaved two-switch forward soft-switching power converter is proposed in the order to minimize an idle circulating current due to the tapped inductor filter without of any additional active auxiliary resonant-assisted snubber circuits, such as active resonant DC link snubbers and AC link snubbers, active resonant commutation leg link snubbers. The unique advantages of this power converter are less power circuit components and power semiconductor devices, constant frequency PWM scheme, cost effective configuration and wider soft-switching PWM operation range under PWM power regulations load variations. The practical effectiveness of the proposed soft-switching converter circuit topology is tested by simulations and is proved by experimental results received from the 500W-100kHz breadboard setup.

• Journal of Power Electronics
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• v.16 no.6
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• pp.2099-2108
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• 2016

The cascaded multilevel converter is widely adopted to medium/high voltage and high power electronic applications due to the small harmonic components of the output voltage and the facilitation of modularity. In this paper, the operation principle of a T-type H-bridge topology is investigated in detail, and a carrier phase shifted pulse width modulation (CPS-PWM) based control method is proposed for this topology. Taking a virtual five-level waveform achieved by a unipolar double frequency CPS-PWM as the output object, PWM signals of the T-type H-bridge can be obtained by reverse derivation according to its switching modes. In addition, a control method for the T-type H-bridge based cascaded multilevel converter is introduced. Then a single-phase T-type H-bridge cascaded multilevel static var generator (SVG) prototype is built, and a repetitive controller based compound current control strategy is designed with the DC-link voltage balancing control scheme analyzed. Finally, simulation and experimental results validate the correctness and feasibility of the proposed modulation method and control strategy for T-type H-bridge based cascaded multilevel converters.

• The Journal of the Convergence on Culture Technology
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• v.9 no.1
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• pp.525-530
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• 2023

Although double-stage hanger is used in many homes for its space utilization and ease of installation, it is inconvenient for users to take off clothes hung on the upper bar due to its high height. Therefore, this paper proposes a new type of double-stage hanger that allows users to easily hang or take out clothes hung on the upper bar while maintaining the function of the existing double-stage hanger. 4-bar link mechanism is applied so that the upper bar can come down to a convenient height with one operation. In addition, an appropriate link shape, length, and joint type are selected so that the height is adjusted three-dimensionally to prevent overlapping of clothes hanging on upper/lower bars. FEA analysis is performed to ensure that the presented hanger shape can support the load of clothes during height adjustment and the feasibility of the three-dimensional height adjustment hanger is verified through fabrication.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.246-247
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• 2017

단상 ac/dc, dc/ac 시스템의 경우, ac와 dc사이의 전력 불균형으로 인해 double line frequency ripple power가 발생한다. 이는 harmonic disturbance을 야기시킨다. 일반적으로 전력 리플을 줄이기 위하여 dc-link에 용량이 큰 전해 커패시터를 사용하는데, 용량이 큰 전해 커패시터는 높은 equivalent series resistance(ESR)을 가지며, 상대적으로 짧은 수명을 갖는 한계를 갖는다. 본 논문은 active power decoupling을 추가함으로써 전해 커패시터를 용량이 작은 필름 커패시터로 대체한 회로 구조를 제시한다. 그리고 dc-link 커패시터 선정방법, 설계한 제어기의 성능과 부하 변동에 따른 실험을 PSIM 시뮬레이션으로 확인하고 실험을 통해 검증한다.

• Journal of Power Electronics
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• v.2 no.4
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• pp.278-287
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• 2002

A novel zero-voltage and zero-current switching PWM DC-DC converter with lowered conduction losses is presented in this paper. A new double two-switch forward high frequency transformer type soft-switching converter topology is developed to minimize circulating currents occurs during freewheeling period. This converter has advantages as less number of the components, simple control principle under constant operation frequency, free of transformer Imbalance effect. The principle of operation is illustrated with steady-state analysis. Moreover, the effectiveness of the proposed converter topology is verified by implementation of a 500w-100kHz breadboard using IGBTs.

• The Journal of the Convergence on Culture Technology
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• v.6 no.1
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• pp.515-520
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• 2020

The design and actual implementation of the four-bar parallel link was studied in the paper. The parallel four-section link is widely used as a basic kinematic mechanism for transmitting the rotation of one axis to the rotational motion of the other axis. However, the parallel 4 link has a problem that phase reversal occurs at the turning point during the movement. In order to prevent the link reversal, it is known that a double parallelogram-type link is formed by attaching an additional phase reversal suppression link with an offset. However, as a result of the actual fabrication experiment, the movement is not smooth at the transition point. In order to solve this problem, in this study, a link for smooth movement is added in addition to a link that provides an offset to prevent phase reversal, so that the phase reversal does not occur at a specific point when the driven shaft rotates along the drive shaft. The test result confirms the validity of our suggestion.

• Journal of Information Technology Services
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• v.20 no.6
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• pp.83-95
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• 2021

In this study, various usage patterns were analyzed after establishing a data mart for micro mobility analysis based on the rental history of public bicycles in Seoul. Rental history data is origin-destination data that includes the rental location and time, and the return location and time. About 1500 rental locations were classified according to the characteristics of the location to create a 'station type' dimension. We also created a 'path type' dimension that displays whether the rental location and return location are the same. In addition, a derived variable called speed, which is obtained by dividing the distance used by the time used, is added, and through this, the characteristics of the riding area and the reason for the rental can be estimated. Meanwhile, administrative district link, administrative neighborhood link, and station type link were created to apply network analysis. Through this analysis, the roles and proportions of administrative districts, public facilities, and private facilities engaged in micro-mobility services were visualized. 49.9% of rentals occur at rental offices near transportation facilities, and half of them occur at rental offices near subway stations. The number of rentals during the evening rush hour is more than double that of the morning rush hour. When the path type is unidirectional, there is a fixed destination, so the distance and time used are short, and the movement speed tends to be high. In the case of round-trip, the purpose of use is exercise or leisure, so the distance and time used are long, and the movement speed is slow. It is expected that the results of the analysis can be used as reference materials for selecting new rental locations, providing convenient services for users, and developing user-specialized products.

• Journal of Power Electronics
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• v.17 no.6
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• pp.1587-1599
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• 2017

This paper proposes a real-time implementation of an optimal operation of a double stage grid connected wind power system incorporating an active power filter (APF). The system is used to supply the nonlinear loads with harmonics and reactive power compensation. On the generator side, a new adaptive neuro fuzzy inference system (ANFIS) based maximum power point tracking (MPPT) control is proposed to track the maximum wind power point regardless of wind speed fluctuations. Whereas on the grid side, a modified predictive current control (PCC) algorithm is used to control the APF, and allow to ensure both compensating harmonic currents and injecting the generated power into the grid. Also a type 2 fuzzy logic controller is used to control the DC-link capacitor in order to improve the dynamic response of the APF, and to ensure a well-smoothed DC-Link capacitor voltage. The gained benefits from these proposed control algorithms are the main contribution in this work. The proposed control scheme is implemented on a small-scale wind energy conversion system (WECS) controlled by a dSPACE 1104 card. Experimental results show that the proposed T2FLC maintains the DC-Link capacitor voltage within the limit for injecting the power into the grid. In addition, the PCC of the APF guarantees a flexible settlement of real power exchanges from the WECS to the grid with a high power factor operation.