• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.71-71
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• 2012

현재 전 세계적으로 극한강우의 발생빈도가 점차 높아지고 있으며 홍수량 또한 강도가 커지고 있는 것이 현실이다. 하지만 과거의 홍수발생 빈도에 따라 설계된 홍수방어시설들이 점차 한계를 보이고 있으므로 이를 대비하기위한 구조적 대책뿐만 아니라 홍수피해 발생 가능지역에 사전 예경보를 시행하는 비구조적 대책마련 또한 필요하다. 기존의 홍수예측은 확정적인 하나의 유량예측값만을 제공함으로써 신속하고 편리하였지만 이에 대한 불확실성이 큰 경우 예상치 못한 큰 인적 물적 피해를 가져올 수 있다. 이처럼 확률론적 홍수예측의 필요성이 대두되어 지면서 유럽이나 미국등 선진국에서는 EFFS(European Flood Forecasting System)과 NWSRFS(National Water Service River Forecast System)같이 이미 확률론적 홍수예측에 대한 연구 및 기술개발이 활발하게 진행되어지고 있다. 하지만 홍수예측의 확률론적 접근에 있어서는 많은 불확실성들이 내포되어 있으므로 예측시스템에서 생성된 앙상블 유량예측 결과의 신뢰도 분석과 올바른 불확실성 정보의 제공이 필요하다. 본 연구는 확률론적 홍수예측 방법을 국내에 적용시켜서 기상청의 예측시스템 KLAPS(Korea Local Analysis and Prediction System), MAPLE(McGill Algorithm for Precipitation Nowcasting by Lagrangian Extrapolation), UM(Unified Model) 그리고 MOGREPS(Met Office Global Regional Ensemble Prediction System)으로부터 생성된 기상앙상블을 현재 국토해양부 홍수통제소에서 사용하고 있는 강우-유출모형인 저류함수모형(Storage Function Method)의 입력 자료로 사용한다. 확률론적 홍수예측에서 오는 불확실성을 분석하기 위해서 첫 번째로 제공되는 기상예측 시스템의 시 공간적 스케일 및 대상유역의 공간특성에 따라 어떠한 형태로 전파되어지는지를 분석하였다. 두 번째는 각각의 예측시스템들이 선행기간(Lead time)에 따라 불확실성의 특성이 어떻게 나타나게 되는지를 확인하였다. 이러한 불확실성의 특성을 정확하게 파악하게 된다면 예측에 있어서 현재 갖고 있는 문제점들로부터 개선해 나가야 할 방향을 제시해주어 향후연구에 유용하게 활용될 수 있을 것이다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.3
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• pp.355-366
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• 2022

This paper proposes a microcode-based neural network accelerator controller for artificial intelligence accelerators that can be reconstructed using a programmable architecture and provide the advantages of low-power and ultra-small chip size. In order for the target accelerator to support various neural network models, the neural network model can be converted into microcode through microcode compiler and mounted on accelerator to control the operators of the accelerator such as datapath and memory access. While the proposed controller and accelerator can run various CNN models, in this paper, we tested them using the YOLOv2-Tiny CNN model. Using a system clock of 200 MHz, the Controller and accelerator achieved an inference time of 137.9 ms/image for VOC 2012 dataset to detect object, 99.5ms/image for mask detection dataset to detect wearing mask. When implementing an accelerator equipped with the proposed controller as a silicon chip, the gate count is 618,388, which corresponds to 65.5% reduction in chip area compared with an accelerator employing a CPU-based controller (RISC-V).

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.3 s.106
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• pp.239-248
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• 2006

In this paper, the cryogenically cooled low noise amplifier module for radio telescope receiver front-end using pHE-MT MMIC is designed and fabricated. In the selection of MMIC, the MMIC fabricated with the pHEMTS providing successful cryogenic operation are chosen. They are mounted in the housing using the thin film substrate. In the design of the housing, the absorber and the elimination of the gap between the carrier and the housing as well removed the unnecessary oscillations by its structure. The mismatch is improved by ribbon-tuning to provide the best performance at room temperature. The fabricated module shows the gain of $35dB{\pm}1dB$ and the noise figure of $2.37{\sim}2.57dB$ at room temperature over $21.5{\sim}23.5GHz$. In the cryogenic temperature of $15^{\circ}K$ cooled by He gas, the measured gain was above 35 dB and flatness ${\pm}2dB$ and the noise temperatures of $28{\sim}37^{\circ}K$.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.3
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• pp.276-285
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• 2020

In this study, accelerated chloride diffusion tests were performed on OPC(Ordinary Portland Cement) and FA(Fly Ash) concrete considering three levels o f W/B(Water to Binder) ratio o n 1,095 curing days. The accelerated chloride diffusion coefficient and the passed charge were evaluated in accordance with Tang's method and ASTM C 1202, and the resistance performance to chloride attack improved over time. FA concrete showed excellent resistance performance against chloride penetration with help of pozzolanic reaction. As the result of the passed charge, FA concrete showed durability improvement, "low" grade to "very low" grade, but OPC concrete changed "moderate" grade to "low" grade at 1,095 curing days. After assuming the design variables used for durability design as normal distribution functions, the service life of each case was evaluated by the probabilistic analysis method based on MCS(Monte Carlo Simulation). In FA concrete, the increase of probability of durability failure was lower than that of OPC concrete with increasing time, because the time-dependent coefficient of FA concrete was up to 3.2 times higher than OPC concrete. In addition, the service life by probabilistic analysis was evaluated lower than the service life by deterministic analysis, since the target probability of durability failure was set to 10%. It is considered that more economical durability design will be possible if the mo re suitable target probability of durability failure is set for various structures through researches on actual conditions and indoor tests under various circumstances.

• Korean Journal of Heritage: History & Science
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• v.47 no.3
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• pp.4-23
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• 2014

Seokjojeon Hall is the Neoclassic style building situated in Deoksugung Palace, which was proposed by John McLeavy Brown who was a chief commissioner of the Daehan Empire and designed by John Reginald Hardings in 1897. Construction of the Seokjojeon Hall began in 1900 and completed in 1910 at the total cost of one million won. Decorating and furnishing of the interior was designed by Lovell and all the furniture of Seokjojeon Hall had been purchased from Maple&Co. The Maple&Co was the supplier of luxury furnitures and decorating items for luxurious residentials, hotels, embassies and the palaces and its headquarter was located in London. Ready-made furnitures were purchased as shown in the Maple's catalog. The designs and styles of the west were applied to Seokjojeon Hall. That is one of the aspects showing Daehan Imperial underwent a period of Westernization.

• Journal of Broadcast Engineering
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• v.20 no.1
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• pp.140-152
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• 2015

HCI(Human Computer Interaction) enables the interaction between people and computers by using a human-familiar interface called as Modality. Recently, to provide an optimal interface according to various devices and service environment, an advanced HCI method using multiple modalities is intensively studied. However, the multimodal interface has difficulties that modalities have different data formats and are hard to be cooperated efficiently. To solve this problem, a multimodal communicator is introduced, which is based on EMMA(Extensible Multimodal Annotation Markup language) and MMI(Multimodal Interaction Framework) of W3C(World Wide Web Consortium) standards. This standard based framework consisting of modality component, interaction manager, and presentation component makes multiple modalities interoperable and provides a wide expansion capability for other modalities. Experimental results show that the multimodal communicator is facilitated by using multiple modalities of eye tracking and gesture recognition for a map browsing scenario.

• Journal of the Korea Concrete Institute
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• v.28 no.2
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• pp.149-156
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• 2016

The service life in RC (Reinforced Concrete) is very important and it is usually obtained through deterministic method based on Fick's 2nd law and probabilistic method. This paper presents an evaluation of $P_{df}$(durability failure probability) and the related service life considering time-dependent behaviors in chloride diffusion and surface chloride content. For the work, field investigation is performed for RC structures exposed to chloride attack for 3.5~4.5years, focusing tidal zone (6.0 m) and sea shore (9.0 m), respectively. Random variables like cover depth, chloride diffusion coefficient, and surface chloride content are obtained, and $P_{df}$ and the service life are evaluated. Unlike the results from deterministic method using LIFE 365, probabilistic method with time effects on diffusion and surface chloride shows a relatively rapid change in the result, which is a significant reductions of service life in the case with low surface chloride content. For probabilistic evaluation of durability, high surface chloride content over $10.0kg/m^3$ is required and reasonable service life can be derived with consideration of time-dependent diffusion coefficient.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.12
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• pp.10-19
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• 2012

In this paper, we propose an Adaptive Modulation and Coding (AMC) scheme using relay protocols generally known as Relay Node (RN). The AMC scheme is used for improving the throughput and a reliability of a communication system, because of the nature of different modulation and coding schemes. We analyze the performance of relay protocols with the AMC scheme and observed that relay protocols with the AMC scheme is capable of providing better average throughput at a lower Signal to Noise Ratio (SNR) level as compared to the conventional scheme with no AMC. We perform Monte Carlo simulations with Long Term Evolution-Advanced (LTE-A) parameters to prove the performance comparison of adaptive Modulation and Coding Scheme (MCS) relay protocols with the non-adaptive MCS relay protocols. The simulation results of the proposed system with adaptive MCS prove that among the Amplify-and-Forward (AF), Decode-and-Forward (DF) and DeModulate-and-Forward (DMF), the DMF protocol performs best at a lower SNR value and also provides better average throughput.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.22 no.2
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• pp.79-87
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• 2010

This is the first of the two papers dealing with reliability analyses for external and internal stability of a quay wall constructed on a special foundation. A new practical reliability analysis method is proposed in this paper to evaluate the quantitative risk associated with external stability of a quay wall constructed on the deep cement mixed ground. The method can consider uncertainties in various design variables. For the risk estimation to external stability of the improved soil-quay wall, three corresponding limit state functions of sliding, overturning and bearing capacity are fully defined by introducing concept of the secondary random variable. Three representative reliability methods, MVFOSM, FORM and MCS are then applied to evaluate the failure probabilities of the three limit state functions explicitly expressed in terms of the basic and secondary random variables. From the reliability analysis results, the failure probabilities obtained from the three approaches are very close to each other, and the sliding failure mode appears to be the most critical when the earthquake loading is under consideration.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.1
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• pp.64-75
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• 2009

The shipbuilder's requirement for a higher power output rating has led to the development of a super large two stroke low speed diesel engines. Usually a large-sized bore engine ranging from $8{\sim}14$ cylinders, this engine group is capable of delivering power output of more than 100,000 bhp at maximum continuous rating(mcr). Other positive aspects of this engine type include higher thermal efficiency, reliability, durability and mobility. This plays a vital role in meeting the propulsion requirement of vessels, specifically for large container ships, of which speed is a primary concern to become more competitive. Consequently, this also resulted in the modification of engine parameters and new component designs to meet the consequential higher mean effective pressure and higher maximum combustion pressure. Even though the fundamental excitation mechanisms unchanged, torsional vibration stresses in the propulsion shafting are subsequently perceived to be higher. As such, one important viewpoint in the initial engine design is the resulting vibration characteristic expected to prevail on the propulsion shafting system(PSS). This paper investigated the torsional vibration characteristics of these super large engines. For the two node torsional vibration with a nodal point on the crankshaft, a tuning damper is necessary to reduce the torsional stresses on the crankshaft. Hence, the tuning torsional vibration damper design and compatibility to the shafting system was similarly reviewed and analyzed.