• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.9 s.90
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• pp.903-909
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• 2004

A CFA(cooling fan assembly) is composed of a fan, motor and shroud, which is at the back of the automotive radiator. By forcing the wind to pass, the CFA controls the cooling performance of the radiator. The noise and vibration of the CFA may be primarily due to the resonance between the CFA and engine. The Interference among the fan, shroud and radiator by deformation is considered when the CFA is designed. In this paper, in order to analyze the structural vibration of the CFA for automobiles, a finite element model of the CFA is established by using a commercial FEM code. After the finite element modeling, the natural frequencies and the mode shapes are obtained from the FE analysis. The natural frequencies are obtained from the vibration test as well. Then, the results of the vibration test are compared with those of the FE analysis. The natural frequencies obtained by experiment have a great similarity to the results from FE model. We have confirmed the validity of the FE model and verify the structural safety for the resonance. The stress and displacements are obtained from FE analysis. We have confirmed the safety for the interference and failure.

• Journal of the Korean Electrochemical Society
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• v.6 no.3
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• pp.203-207
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• 2003

Zinc Air batteries obtain their energy density by utilizing ambient oxygen as the cathode materials. And specific capacity of zinc powder is as high as 820 mAh/g. When Zinc Air battery discharged at low current, then discharge voltage profile has very flat pattern until reach to end of voltage. But, when Zinc Air battery discharged at high current, then discharge voltage and energy becomes very low. So we focused on resistance and porosity of cathode with contents of PTFE. Wf studied on the effects of PTFE on performance of Zinc Air batteries. So we have got optimum contents of PTFE binder.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.8
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• pp.109-118
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• 2010

It is expected that distribution system, interconnected with wind turbines, would experience the voltage problem due to WT's output. But most papers just consider this problem using the simulation or the theory only. In this paper, we verify this problem through the measurement at the distribution system and wind turbine. We explain the method for voltage management at distribution system. And we verify that the voltage of D/L interconnected with WTs could not be maintained properly using pole transformer's tap only. We consider some method to solve this problem and we propose the installation of SVR(step voltage regulator). Finally we show this method's validity through the simulation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37A no.9
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• pp.772-779
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• 2012

In the current MANET, DOS or DDOS attacks are increasing, but as MANET has limited bandwidth, computational resources and battery power, the existing traceback mechanisms can not be applied to it. Therefore, in case of traceback techniques being applied to MANET, the resource of each node must be used efficiently. However, in the traceback techniques applied to an existing ad hoc network, as a cluster head which represents all nodes in the cluster area manages the traceback, the overhead of the cluster head shortens each node's life. In addition, in case of multi-hop clustering, as one Cluster head manages more node than one, its problem is getting even worse. This paper proposes TNA(Traceback against Network Attacks) based on multihop clustering using the depth of tree structure in order to reduce the overhead of distributed information management.

• Journal of IKEEE
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• v.21 no.3
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• pp.195-201
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• 2017

High-power wireless transmission system becomes a key technology for the advance of battery-powered devices. The wireless power transfer devices are currently dominated by the inductive and capacitive wireless power transfer systems, which have relatively low power transmission capacity and low efficiency rather than the wired power transmission. The work presented in this paper proposes an alternative method of high-power transmission system, based on a variable speed motor system with a magnetic coupling. It enables high-capacity power transmission, high efficiency, and low possibility of failures, and the performance of the proposed scheme is verified by simulation and experiments.

• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.912-916
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• 2010

국내 통합수자원관리기술 수준은 계속되는 연구와 개발 노력으로 선진국 수준을 따라잡을 것으로 기대되나 개발된 기술의 실용성, 적용효과를 가시적으로 보여주지 못하고 있다. 따라서 본 연구에서는 통합수자원 관리 기술을 적용하고자 강원도 평창군의 평창강 유역을 대상으로 통합수자원관리 전략을 수립한다. 평창강 유역의 대부분이 평창군이라는 하나의 행정구역에 속해 있어 본 연구에서는 평창강 유역 단위로 자료의 수집이 어려운 부문은 평창군을 기준으로 수집하여 분석하였다. 이수, 치수, 환경, 조직 및 정책 부문으로 나누어 평창군의 수자원 현황을 파악하고 평창군 수자원관리의 강점, 약점, 기회, 위협 요인을 분석(SWOT 분석)하였다. 그 결과 평창군의 강점은 수자원에 대한 관심이 높고, 관련 문제를 해결하고자 하는 의지가 강하다는 것이다. 약점은 수자원관리를 위한 총괄조직이 없다는 것이고, 위협요인은 기후변화에 따른 국지성 집중 호우로 홍수피해 위험성이 증가하고 있다는 점이다. 반면, 평창군의 기회요인으로는 동계올림픽 유치를 위한 노력이 계속되고 있어 토지 및 수자원 개발 측면에서도 좋은 기회가 될 수 있다. SWOT 분석의 결과를 고려하여 통합수자원관리를 위한 전략을 제안하였다. 평창군 물문제 해결을 위한통합수자원관리 실행을 목표로 '평창물관리위원회' 설치를 제안하였다. 그리고 평창군의 통합수자원관리 기반을 조성하기 위해서는 이해당사자의 참여가 필요하며, 평창군 통합수자원관리지원시스템 구축을 제안하였다. 이러한 전략에 따라 강원도 평창군에서는 '평창군 물관리위원회 운영 조례(2009.9.11, 평창군 조례 제1919호)'가 제정되었고 평창군 물관리위원회를 이끌어갈 위원들의 구성도 마무리되었으며, 이를 지원할 평창군 통합수자원관리 지원 시스템도 구축되어 운영되고 있다. 앞으로의 계획은 2010년 4월 평창군 물관리위원회 창립총회를 시작으로 평창군 스스로 위원회를 운영하고 물관리 비전을 설정하고 실행계획을 수립할 수 있도록 지원할 계획이며;구축된 평창군 통합수자원관리지원시스템의 운영을 활성화하는 것이다. 이와 같은 통합수자원관리 적용 노력을 통합수자원관리 성공 사례로 발전시켜 나아가 국내는 물론 국외에서도 좋은 모델로 활용할 수 있을 것이다.

• Journal of the Korean Society for Railway
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• v.14 no.2
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• pp.100-108
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• 2011

This paper investigates the structural stability and reliability on improving performance of flexible brake pad used in high speed train. To this end, an improved model of flexible pad was obtained through structural analysis. Brake pad specimens were subjected to modal, stroke and endurance tests to examine the dynamic characteristics and mechanical stability. The hot spot generation with increasing rotational speed was observed on chassis dynamometer equipment and then the structurally uniform contact between the disc and pad was achieved. The temperature distribution of flexible pad was measured using the infrared camcorder. Hence, the proposed flexible pad showed the better structural stability and thermal energy emission.

• Journal of Fashion Business
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• v.24 no.1
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• pp.15-28
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• 2020

The purpose of this study was to develop and propose creative smart bags in emotional e-textiles using LEDs that inform smartphone users of motion-induced luminescence and ringing of cell phones. The LED light-emitting operation tasks produced in the study were applied to each of the three design smart bags, setting the five cases of luminance by a call initiated, absent phone, rejecting answering phone, texting, and motion-induced luminescence. In the male laptop bags of LED luminous images using wappen, 10 LEDs could be separated by a total of three pins to display the luminous mode, and all 10 LEDs became a total of five luminous patterns, including all that illuminate and those that illuminate randomly. E-wappen rendered the motif a strong sense of visibility and performed six roles on phone rings and texting. To develop a women's tote bag, we did a laser cut and attached the leather strips and placed 10 triangular LEDs to form a geometric LED e-textile. It provides the possibility of transforming simple design from traditional fashion into a more interesting and various smart designs. An entertainment smart bag using graphic design was constructed by applying a tilt sensor to look like a light in the night sky by shaking and moving the bag. The graphic design and composition of LEDs indicate that LEDs and fashion item are applied in harmony rather than heterogeneous, enabling them to be applied as fashion-oriented wearable smart products.

• Journal of Fashion Business
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• v.24 no.3
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• pp.17-29
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• 2020

This study aimed to produce fiber stretch sensors for smart soccer socks to prevent injuries during training. A sensor was manufactured with stretchable fabric and tested to ensure convenience during training. In order to manufacture the fiber stretch sensor, a CNT dispersion solution was applied to an e-band and elastic polyester fabric, and the performance of the sensors was evaluated by a tensile test. Performance evaluation showed that both of the tested fabrics are excellent for this purpose. Both sensors were attached to socks to create prototype wearable devices, and an experiment was conducted to determine whether a resistance change accompanying relaxation and contraction of the gastrocnemius muscle could be detected. In order to accurately evaluate performance as a sensor, the fabric was stretched 20 times at low speeds of 1 Hz and 0.5 Hz. A change in resistance due to tension was observed, with both the E-band and the stretchable poly fabric showing high sensitivity and high reproducibility. Both can be used as relaxation/contraction sensors. Smart soccer socks were made using the two materials, and an evaluation was conducted. Tensile tests were done on the smart soccer socks; the tests were done 20 times per sock, and the sensor showed a stable resistance change between 30 and 40 ohms depending on the tension of the sensor. As a result, we confirmed that smart soccer socks with stretch sensors made of E-bands can measure changes in the gastrocnemius muscle.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.11a
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• pp.387-390
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• 2005

A This paper presents a novel three-phase current-fed Pulse Width Modulation converter with switched- capacitor type resonant DC link commutation circuit operating PWM pattern strategy under a design consideration of low-pass filter, which can operate on the basis of the principle of zero current soft-switching commutation. In the first place, the steady-state operating principle of this converter with a new resonant DC link snubber circuit is described in connection with the equivalent operation circuit, together with the practical design procedure of the switched-capacitor type resonant DC link circuit is discussed from a theoretical viewpoint on the basis of a design example for high-power applications. The actively delayed time correction method to compensate distorted currents due to a relatively long resonant commutation time is newly implemented in the open loop control scheme so as to acquire the new optimum PWM pattern. Finally, the experiment or set-up in laboratory system or this converter is concretely demonstrated herein to confirm a zero current soft-switching commutation of this converter. The comparative evaluations between current-fed hard switching PWM and soft-switching PWM converters are carried out from a viewpoint of their PWM converter characteristics.