• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2021년도 춘계학술대회
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• pp.197-199
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• 2021

고속화 되고 있는 철도 시스템은 각 구성 요소의 자동화를 넘어 이를 통합한 스마트 철도 네트워크로 진화되고 있다. 이와 같은 스마트 철도 네트워크를 구축하기 위해서는 LTE-R이나 5G-R과 같은 모바일 통신 기술 뿐만 아니라 AI, 빅데이터, 딥러닝과 같은 융복합 정보기술의 활용이 필수적이다. 본 연구에서는 이와 같이 스마트 철도 네트워크를 위한 철도 통신의 구조를 제안하고자 한다. 본 연구에서 제안하는 스마트 철도 네트워크 통신 구조는 고속철도의 안전 운행, 철도 관리 및 고객 서비스를 포괄하는 구조로 구성되며 필요에 따라 이를 혼합한 기능을 가질 수도 있다. 본 연구의 결과는 스마트 철도 네트워크의 구축과 운영 및 유지 관리, 철도통신 시스템 표준의 개발 등에 도움을 줄 수 있을 것으로 생각한다.

• Journal of Mechanical Science and Technology
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• 제20권5호
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• pp.612-620
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• 2006

This paper proposes an optimal trajectory generation method for biped robots for walking up-and-down stairs using a Real-Coded Genetic Algorithm (RCGA). The RCGA is most effective in minimizing the total consumption energy of a multi-dof biped robot. Each joint angle trajectory is defined as a 4-th order polynomial of which the coefficients are chromosomes or design variables to approximate the walking gait. Constraints are divided into equalities and inequalities. First, equality constraints consist of initial conditions and repeatability conditions with respect to each joint angle and angular velocity at the start and end of a stride period. Next, inequality constraints include collision prevention conditions of a swing leg, singular prevention conditions, and stability conditions. The effectiveness of the proposed optimal trajectory is shown in computer simulations with a 6-dof biped robot model that consists of seven links in the sagittal plane. The optimal trajectory is more efficient than that generated by the Modified Gravity-Compensated Inverted Pendulum Mode (MGCIPM). And various trajectories generated by the proposed GA method are analyzed from the viewpoint of the consumption energy: walking on even ground, ascending stairs, and descending stairs.

• 인터넷정보학회논문지
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• 제20권3호
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• pp.129-135
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• 2019

최근 들어 전 세계적으로 추진되고 있는 5G가 4차 산업혁명에서 데이터의 흐름을 책임질 신경망 역할을 담당하고 향후 관련 시장에 대한 막대한 가치를 창출할 것으로 예상되고 있다. 하지만 5세대 네트워크의 장밋빛 전망과 5G 개통에 있어 선도적 위치에도 불구하고, 네트워크 사업자들은 5G 네트워크의 온전한 구축을 주저하고 있다. 이는 구축비용을 상회하는 사업모델이 부재하여 네트워크 사업들자이 막대한 구축비용의 회수가 어렵다고 판단하고 있기 때문이다. 더불어 5G의 사업 환경을 종합적으로 조사하거나 분석한 연구가 부족한 실정이다. 본 연구는 5G 실용화 및 활성화에 필수불가결한 관련 기술, 서비스, 정부정책 그리고 사업모델에 관한 연구이슈를 포괄적으로 제안하고 발전적 제언을 제시하였다.

• 한국게임학회 논문지
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• 제20권5호
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• pp.3-12
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• 2020

5세대 통신기술(5G)의 도입은 4세대 통신기술(4G)에서 발생했던 서비스 트래픽 속도와 용량 문제를 크게 감소시켰다. 이러한 통신환경에서 클라우드 게임의 시장 수요는 높아지고 있으며 향후 모바일 게임을 대체하는 분야로 클라우드 게임이 각광받고 있다. 본 연구에서는 통신기술의 발전에 따른 게임 산업의 변화와 클라우드 게임의 특징 및 시장 현황을 설명한다. 다음으로 클라우드 게임의 경쟁우위 요소로서 독창적인 게임콘텐츠, 안정적인 게임 환경, 높은 플랫폼 접근성을 제시한다. 본 연구는 클라우드 게임에 대한 독자의 이해를 높이며, 클라우드 게임 시장 및 산업을 위한 정책적 지원과 관련된 의사결정을 돕기 위한 자료로 활용될 수 있을 것이다.

• International Journal of Computer Science & Network Security
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• 제23권5호
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• pp.121-127
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• 2023

A 500 km/h linear motor high speed terrestrial transportation service is planned to launch 2027 in Japan. In order to support 5G service in the train, the Sub-carrier spacing frequency of 30 kHz is planned to be used instead of common 15 kHz sub-carrier spacing to mitigate Doppler effect in such high-speed transportation. In addition, to increase the cell size of 5G mobile system, plural Base Station antenna will transmit the identical Down Link (DL) signal to form the expanded cell size along the train rail. In this situation, forward and backward antenna signals will be Doppler shifted by reverse direction respectively and the receiver in the train might suffer to estimate accurate Channel Transfer Function (CTF) for its demodulation. In this paper, Delay and Doppler Profiler (DDP) based Channel Estimator is proposed and it is successfully implemented in signal processing simulation system. Then the simulated performances are compared with the conventional Time domain linear interpolated estimator. According to the simulation results, QPSK modulation can be used even under severe channel condition such as 500 km/h, 2 path reverse Doppler Shift condition, although QPSK modulation can be used less than 200 km/h with conventional Channel estimator.

• 설비공학논문집
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• 제19권7호
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• pp.500-511
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• 2007

The Optimal solutions of the design variables in internally finned tubes have been obtained for three-dimensional periodically fully developed turbulent flow and heat transfer. For a trapezoidal fin profile, performances of the heat exchanger are determined by considering the heat transfer rate and pressure drop, simultaneously, that are interdependent quantities. Therefore, Pareto frontier sets of a heat exchanger can be acquired by integrating CFD and a multi-objective optimization technique. The optimal values of fin widths $(d_1,\;d_2)$, fin height(h) and helix angle$(\gamma)$ are numerical1y obtained by minimizing the pressure loss and maximizing the heat transfer rate within ranges of $d_1=0.5\sim1.5mm$, $d_2=0.5\sim1.5mm$, $h=0.5\sim1.5mm$, and $\gamma=0\sim20^{\circ}$. For this, a general CFD code and a global genetic algorithm(GA) are used. The Pareto sets of the optimal solutions can be acquired after $30^{th}$ generation.

• 융합정보논문지
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• 제10권7호
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• pp.1-6
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• 2020

본 논문에서는 셀 간 정보의 공유를 통한 협력이 가능한 연결된 네트워크 구조를 갖는 5G Cloud RAN 네트워크에 적용이 가능한 새로운 자원 관리 알고리즘을 제안한다. 제안 알고리즘은 네트워크 협력의 이점을 활용하여 공정성과 처리량을 동시에 증가시킨다. 이러한 네트워크 성능 최적화는 허용이 가능한 양의 신호 처리 오버헤드 및 계산 복잡도 내에서 달성될 수 있으며 시뮬레이션 결과는 셀 외곽 사용자에 대한 네트워크 용량이 기존의 방법 대비 40% 가량 향상되었으며 사용자간 공정성 또한 Jain의 공평성 지수를 기준으로 약 23% 향상되었음을 확인하였다.

• 한국안전학회지
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• 제36권5호
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• pp.1-9
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• 2021

With the convergence of the information and communication technologies, a new age of technological civilization has arrived. This is the age of intelligent revolution, known as the 4th industrial revolution. The 4th industrial revolution is based on technological innovations, such as robots, big data analysis, artificial intelligence, and unmanned transportation facilities. This revolution would interconnect all the people, things, and economy, and hence will lead to the expansion of the industry. A high-density, high-capacity energy technology is required to maintain this interconnection. As a next-generation energy source, lithium-ion batteries are in the spotlight today. However, lithium-ion batteries can cause thermal runaway and fire because of electrical, thermal, and mechanical abuse. In this study, thermal runaway was induced in 72.5 Ah NCM pouch-type lithium-ion batteries because of thermal abuse. The surface of the pouch-type lithium-ion batteries was heated by the hot plate heating method, and the effect of the rate of increase in the surface temperature on the thermal runaway trigger time was analyzed using Minitab 19, a statistical analysis program. The correlation analysis results confirmed that there existed a strong negative relationship between each variable, while the regression analysis demonstrated that the thermal runaway trigger time of lithium-ion batteries can be predicted from the rate of increase in their surface temperature.

• 신재생에너지
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• 제7권2호
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• pp.10-17
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• 2011

Korea is the 11th largest energy consumption country and 96% of its total energy consumption depends on imports from overseas. Therefore it is a very important task to secure renewable energy sources which can reduce both the carbon-dioxide emission and dependency on overseas energy imports. Among the various renewable energy sources, organic wastes are important sources. In Korea, 113 million toe of methane is generated from organic wastes annually, but only 3.7% is effectively used for energy conversion. Thus, it is very important to make better use of organic wastes, especially for power generation. The goals of this project are to develope the fuel supplying system of Bio Gasturbine (GT) for 5MW-class co-generation system. The fuel supplying system mainly consists of $H_2S$ removal system, Bio Gas compression system, Siloxane removal system and moisture separating systems. The fuel requirement of 5MW-class GT is at around 60% of $CH_4$, $H_2S$ (<30 ppm), Siloxane(<10 mg/$nm^3$) and supply pressure (> 25 bar) from biogas compressor. Main mechnical charateristics of Bio Gasturbine system have the specific performance; 1) high speed turbine speed (12,840 rpm) 2) very clean emmission NOx (<50 ppm) 3) high efficiency of energy conversion rate. This paper focuses on the development of design technology for food waste biogas pretreatment system for 5MW-class biogas turbine. The study also has the plan to replace the fuel of gas turbine and other distributed power systems. As the increase of bioenergy, this system help to contribute to spread more New & Renewable Energy and the establishment of Renewable Portfolio Standards (RPS) for Korea.

• 분석과학
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• 제30권1호
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• pp.49-56
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• 2017

Here, we demonstrate surface functionalization of Au chips with 4-(carboxymethyl)aniline (CMA) and amine-terminated polyamidoamine (PAMAM) dendrimers for immobilization of antibodies on the Au surfaces. Use of the functionalization strategy led to high surface density of the immobilized antibodies on the Au chips. Specifically, we found that the functionalization of Au chips with CMA and amine-terminated $6^{th}$ generation PAMAM dendrimers allowed immobilization of immunoglobulin (IgG) antibodies with high surface density, which is 5 times higher than that obtained with Au surfaces functionalized with CMA and ethylenediamine.