• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.5
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• pp.91-100
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• 2018

The new seismic retrofit system in study propose is the Dual system, which aims to be applied to the seismically vulnerable low-story buildings. The Dual system is composed of existing structure, external retrofit frame and hysteretic steel dampers installed between former two components. The Dual system dissipates the energy by plastic deformation of steel damper caused by relative displacement due to the differences in stiffness, weight, and eigenperiod of each components. The dynamic test with shaking table was performed to verify the seismic performance of the proposed Dual system. As a result of the dynamic test, it is expected that the Dual system will improve the seismic performance due to the reduction of strain of 56% and the damage reduction of 93%, even though the energy is 1.84 times higher than that of the dual system. And the results of the study are presented as basic data of the study for setting the design range of the dual system.

• KEPCO Journal on Electric Power and Energy
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• v.6 no.2
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• pp.129-135
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• 2020

The standardization of e-IoT (energy Internet of Things) communication and service, which is the energy field of energy, is to define the standard model and to demonstrate the practical model in order to take the lead and occupy the market where new market is created with the latest technology. In particular, detailed technical specifications are defined for developing a framework for IoT technology, the foundation technology of the 4th Industrial Revolution, securing interoperability through standardization, and operating a standard platform. In this paper, we propose a method for e-IoT standard protocol lightening and test certification procedure. The proposed method provides a product implementation method that can solve the problem of low power issue of e-IoT product in the future.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.7
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• pp.1589-1598
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• 2014

To support the WBAN, IEEE 802.15 Task Group 6 announced standardized documents on technical requirements of the PHY and MAC. In the IEEE 802.15.6 MAC protocol, CSMA/CA(Carrier Sense Multiple Access with Collision Avoidance) algorithm is performed based on the eight-level priorities according to the type of traffics of the periodic data from medical sensor nodes. Several nodes, which detected the changed bio signals, transmit emergency data at the same time, so latency could be higher than emergency latency and energy consumption will increase. In this thesis, we proposed a CSMA/CA algorithm in WBAN to solve these problems. Simulations are performed using a Castalia based on the OMNeT++ network simulation framework to estimate the performance of the proposed superframe and algorithms. Performance evaluation results show that the packet transmission success rate and energy efficiency are improved by reducing the probability of collision using the proposed MAC protocol.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.10a
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• pp.206-213
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• 2013

Transient response of a crack in a functionally graded piezoelectric material (FGPM) interface layer between two dissimilar homogeneous piezoelectric layers under anti-plane shear is analyzed using integral transform approaches. The properties of the FGPM layer vary continuously along the thickness. Laplace and Fourier transforms are used to reduce the problem to two sets of dual integral equations, which are then expressed to the Fredholm integral equations of the second kind. Numerical values on the dynamic energy release rate (DERR) are presented for the FGPM to show the effects on electric loading, gradient of the material properties, and thickness of the layers. Computed results yield following conclusions: (a) the DERR increases with the increase of the gradient of the material properties of the FGPM layer; (b) certain direction and magnitude of the electric impact loading impedes crack extension; (c) increase of the thickness of the FGPM layer and the homogeneous piezoelectric layer which has larger material properties than those of the crack plane are beneficial to increase of the resistance of transient fracture of the FGPM layer.

• Journal of KIISE:Software and Applications
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• v.27 no.8
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• pp.804-814
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• 2000

In this paper, we propose an effective method to detect the regions of interests in the Videostrobokymography System. Videostrobokymography system is a medical image processing system for extracting automatically the diagnosis parameters from the irregular vibratory movements of the vocal fold. We detect the regions of interests through three steps. In the first step, we remove the noise in the input image and we find the minimum energy value in each frame. In the second step, we computed the edge by everage value for the one line. In the third step, the regions of interests can be extracted by using the Merge Algorithm which uses the variance of luminance as the feature points. We experimented this method for the vocal fold images of nineteen patients. In consequence, the regions of interests are detected in most vocal fold images. The method proposed in this study is efficient enough to extract the region of interests in the vocal fold images with the frame rate of 40 frames/second and the resolution of 200${\times}$280 pixels.

• Journal of Software Assessment and Valuation
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• v.17 no.2
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• pp.161-172
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• 2021

Neuromorphic architecture is drawing attention as a next-generation computing that supports artificial intelligence technology with low energy. However, FPGA embedded boards based on Neuromorphic architecturehave limited resources due to size and power. In this paper, we compared and evaluated the image reduction method using the interpolation method that rescales the size without considering the feature points and the DCT (Discrete Cosine Transform) method that preserves the feature points as much as possible based on energy. The scaled images were compared and analyzed for accuracy through CNN (Convolutional Neural Networks) in a PC environment and in the Nengo framework of an FPGA embedded board.. As a result of the experiment, DCT based classification showed about 1.9% higher performance than that of interpolation representation in both CNN and FPGA nengo environments. Based on the experimental results, when the DCT method is used in a limited resource environment such as an embedded board, a lot of resources are allocated to the expression of neurons used for classification, and the recognition rate is expected to increase.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2022.06a
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• pp.317-318
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• 2022

In accordance with global decarbonization, optimization and productivity improvement using digital twin are being sought, and software development for optimizing ship and marine energy operation is accelerating by selecting digital twin as a future core technology. In order to reduce the operating cost of ships and strengthen the competitiveness of the shipbuilding industry due to the international strengthening of regulations on carbon emissions, it is necessary to predict the carbon emission of ships in advance and provide a carbon reduction operation solution. A plan was carried out for the development of open digital platform technology and the establishment of an environment to support the securing of carbon transparency of the ship and offshore system.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.304-304
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• 2012

III-V 화합물 태양전지는 실리콘 등 다른 태양전지에 비해 1sun상 30% 이상의 고효율을 갖고 있고 direct bandgap과 높은 이동도 등의 물질특성과 3족과 5족의 비율 조절로 같은 결정구조에서 에너지 bandgap이 다른 물질들을 만들기에 용이하여 태양전지 스펙트럼의 넓은 영역을 흡수할 수 있는 장점이 있다. 그러나 셀 자체의 물질이 실리콘에 비하여 고가여서 고성능이 요구되는 우주 인공위성 등에 적용이 되었지만, 2000년대 이후로 집광에 적용 가능한 태양전지의 연구를 거듭하여 2005년부터는 값싼 프레넬 렌즈를 이용하여 1 sun에 비해 500배 해당하는 빛을 셀에 집광하여 보다 효율을 증가시킴으로써 지상발전용에도 적용 가능한 셀을 형성하게 되었다. 더불어 태양전지의 효율을 증가시키기 위한 다양한 구조적 변화의 시도도 많이 이루어지고 있다. 최근 실리콘 태양전지의 표면에 texture 구조를 주어 높은 흡수율과 낮은 반사율을 갖게 함으로써 효율을 증가시키는 사례가 많아지고, III-V 화합물 태양전지도 texturing에 의해 증가된 효율을 발표한바 있다. 본 연구에서는 III-V 화합물 InGaP 태양전지의 window층으로 사용되는 InAlP 층에 Metal-assisted chemical etching (mac etching) 방법으로 texture 구조를 형성하여 etching 시간에 따른 InAlP층의 표면 변화와 반사율의 변화를 분석하였다.

• Proceedings of the KIEE Conference
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• 2008.10b
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• pp.534-535
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• 2008

최근 유비쿼터스 기술이 급속도로 발전함에 따라 많은 application들이 다양한 환경에서 통신서비스를 요구하고 있다. 이를 지원하기 위하여 많은 무선 센서 네트워킹 기술들이 제안되었지만 제한된 대역쪽과 높은 에러율로 인하여 이동성을 지원하기에는 부족하였다. 특히, 경로를 획득하기 위한 Route Request (RREQ)의 잦은 브로드캐스트 과정은 오히려 혼잡 및 에너지 소모를 야기시키며 네트워크 성능을 저하시키는 문제점이 있다. 본 논문에서는 언제, 어디서나 다양한 토폴로지 환경에서 자가 구성이 가능하며, 이동성을 지원하는 Tree기반의 Self-Routing 기법을 제안한다. 기존의 센서 네트워크내 멀티홉 라우팅 프로토콜과는 달리, 라우터 혹은 싱크노드의 비컨 프레임내 Association 정보만을 이용하여 새로운 라우팅 테이블을 형성함으로써 컨트롤 패킷의 오버 헤드를 크게 줄일 수 있다. 성능 평가를 위하여 실제 모바일 로봇을 이용한 실험과 시뮬레이션을 동시에 하였으며, 기존의 기법보다 향상된 성능을 가짐을 보인다.

• The KIPS Transactions:PartB
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• v.13B no.4 s.107
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• pp.361-368
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• 2006

In this paper we present a snake-based scheme for efficiently detecting contours of objects with boundary concavities. The proposed method is composed of two steps. First, the object's boundary is detected using the proposed snake model. Second, snake points are optimized by inserting new points and deleting unnecessary points to better describe the object's boundary. The proposed algorithm can successfully extract objects with boundary concavities. Experimental results have shown that our algorithm produces more accurate segmentation results than the conventional algorithm.